Toward Precision in Critical Care Research: Methods for Observational and Interventional Studies

Critical care trials evaluate the effect of interventions in patients with diverse personal histories and causes of illness, often under the umbrella of heterogeneous clinical syndromes, such as sepsis or acute respiratory distress syndrome. Given this variation, it is reasonable to expect that the effect of treatment on outcomes may differ for individuals with variable characteristics. However, in randomized controlled trials, efficacy is typically assessed by the average treatment effect (ATE), which quantifies the average effect of the intervention on the outcome in the study population. Importantly, the ATE may hide variations of the treatment's effect on a clinical outcome across levels of patient characteristics, which may erroneously lead to the conclusion that an intervention does not work overall when it may in fact benefit certain patients. In this review, we describe methodological approaches for assessing heterogeneity of treatment effect (HTE), including expert-derived subgrouping, data-driven subgrouping, baseline risk modeling, treatment effect modeling, and individual treatment rule estimation. Next, we outline how insights from HTE analyses can be incorporated into the design of clinical trials. Finally, we propose a research agenda for advancing the field and bringing HTE approaches to the bedside.

Interaction Between State-Level Cigarette Prices and County-Level Tobacco 21 Coverage on Cigarette Smoking Outcomes Among US Adolescents

PURPOSE

To examine whether Tobacco 21 (T21) law coverage moderated associations between cigarette prices and adolescent smoking and associated disparities.

METHODS

We used nationally representative, repeated cross-sectional 2014-2020 Monitoring the Future study data (n = 20,547-96,083) to examine associations between state-level average cigarette price per pack and county-level T21 coverage (100% vs. < 100%) on past 30-day smoking participation, first and daily cigarette smoking initiation, and smoking intentions in US adolescents in eighth, 10th, and 12th grade. We implemented weighted, grade-stratified, modified Poisson regression models to test for interactions between price and T21 coverage for each outcome. We also tested for disparities by sex, race and ethnicity, parental education, and college educational expectations.

RESULTS

Higher cigarette prices were associated with a lower probability of past 30-day smoking participation among eighth graders in counties with < 100% T21 coverage (average marginal effect = -0.003, 95% confidence interval = -0.006, 0.000) but not among eighth graders in counties with 100% T21 coverage (average marginal effect = 0.001, 95% confidence interval = -0.001, 0.004) (p for interaction = 0.005). There were no associations with other smoking outcomes or grades or evidence of differential associations by sociodemographic factors.

DISCUSSION

Our findings suggested that higher cigarette prices were associated with lower adolescent smoking among eighth graders living in counties with < 100% T21 coverage. However, no such association was observed in other grades or smoking outcomes. Further investigation is necessary to determine the best combination of policies to reduce adolescent smoking, related sociodemographic disparities, and the use of other tobacco products in areas with fewer tobacco control policies.

Do movement behaviours influence the association between early menarche and depression symptoms among Brazilian adolescents?

Early menarche has been associated with adverse health outcomes, such as depressive symptoms. Discovering effect modifiers across these conditions in the pediatric population is a constant challenge. We tested whether movement behaviours modified the effect of the association between early menarche and depression symptoms among adolescents. This cross-sectional study included 2031 females aged 15-19 years across all Brazilian geographic regions. Data were collected using a self-administered questionnaire; 30.5% (n = 620) reported having experienced menarche before age 12 years (i.e., early menarche). We used the Patient Health Questionnaire (PHQ-9) to evaluate depressive symptoms. Accruing any moderate-vigorous physical activity during leisure time, limited recreational screen time, and having good sleep quality were the exposures investigated. Adolescents who experienced early menarche and met one (B: -4.45, 95% CI: (-5.38, -3.51)), two (B: -6.07 (-7.02, -5.12)), or three (B: -6.49 (-7.76, -5.21)), and adolescents who experienced not early menarche and met one (B: -5.33 (-6.20; -4.46)), two (B: -6.12 (-6.99; -5.24)), or three (B: -6.27 (-7.30; -5.24)) of the movement behaviour targets had lower PHQ-9 scores for depression symptoms than adolescents who experienced early menarche and did not meet any of the movement behaviours. The disparities in depressive symptoms among the adolescents (early menarche vs. not early menarche) who adhered to all three target behaviours were not statistically significant (B: 0.41 (-0.19; 1.01)). Adherence to movement behaviours modified the effect of the association between early menarche and depression symptoms.

Going beyond the comparison: toward experimental instructional design research with impact

To design effective instruction, educators need to know what design strategies are generally effective and why these strategies work, based on the mechanisms through which they operate. Experimental comparison studies, which compare one instructional design against another, can generate much needed evidence in support of effective design strategies. However, experimental comparison studies are often not equipped to generate evidence regarding the mechanisms through which strategies operate. Therefore, simply conducting experimental comparison studies may not provide educators with all the information they need to design more effective instruction. To generate evidence for the what and the why of design strategies, we advocate for researchers to conduct experimental comparison studies that include mediation or moderation analyses, which can illuminate the mechanisms through which design strategies operate. The purpose of this article is to provide a conceptual overview of mediation and moderation analyses for researchers who conduct experimental comparison studies in instructional design. While these statistical techniques add complexity to study design and analysis, they hold great promise for providing educators with more powerful information upon which to base their instructional design decisions. Using two real-world examples from our own work, we describe the structure of mediation and moderation analyses, emphasizing the need to control for confounding even in the context of experimental studies. We also discuss the importance of using learning theories to help identify mediating or moderating variables to test.

Interplay between polygenic risk score and solar insolation: Implication for systemic lupus erythematosus diagnosis and pathogenesis

OBJECTIVES

This research elucidates the correlation between solar radiation insolation, polygenic risk score (PRS), and systemic lupus erythematosus (SLE) diagnosis, utilizing genomic, environmental, and clinical data.

METHODS

We included 1,800 SLE participants and 1,800 controls from the Taiwan Precision Medicine Initiative, genotyped via the Affymetrix Genome-Wide TWB 2.0 SNP Array. The study employed a SLE-PRS tailored for individuals of Taiwanese ancestry, comprising 27 single nucleotide polymorphisms (SNPs). QGIS computed solar radiation insolation from participants' residences. We employed logistic regression to investigate the associations between SLE-PRS, solar insolation susceptibility, and SLE. Additive and multiplicative interactions were utilized to assess the interactions between solar insolation and SLE-PRS regarding the risk of SLE.

RESULTS

SLE patients showed decreased solar insolation (p < 0.001). The highest decile of SLE-PRS exhibited a statistically significant lower solar insolation 1, 3, 6, and 12 months prior to diagnosis as compared to the lowest decile. Specifically, there were significant differences observed at 1 and 12 months (p = 0.025 and p = 0.004, respectively). It suggests that higher SLE-PRS correlated with reduced solar insolation tolerance. We observed an increase in SLE risk across ascending SLE-PRS percentiles exclusively in the high solar insolation group, not in the low solar insolation group. However, the interaction effect of SLE-PRS and solar insolation on SLE risk is not statistically significant. Compared to the lowest decile, the highest SLE-PRS decile showed a 10.98-fold increase in SLE risk (95 % CI, 3.773-31.952, p < 0.001). High SLE-PRS scores in conjunction with high solar insolation contribute to SLE incidence.

CONCLUSIONS

Our study unveils the intertwined nature of UV insolation and polygenic risks in SLE. Future studies should explore the preventative potential of robust solar radiation protection for high-risk individuals before the disease onset.

Estimating and presenting hazard ratios and absolute risks from a Cox model with complex nonlinear interactions

Interaction analysis is a critical component of clinical and public health research and represents a key topic in precision health and medicine. In applied settings, however, interaction assessment is usually limited to the test of a product term in a regression model and to the presentation of results stratified by levels of additional covariates. Stratification of results often relies on categorizing or making linearity assumptions for continuous covariates, with substantial loss of precision and of relevant information. In time-to-event analysis, moreover, interaction assessment is often limited to the multiplicative hazard scale by inclusion of a product term in a Cox regression model, disregarding the clinically relevant information that is captured by the absolute risk scale. In this paper we present a user-friendly procedure, based on the prediction of individual absolute risks from the Cox model, for the estimation and presentation of interactive effects on both the multiplicative and additive scales in survival analysis. We describe how to flexibly incorporate interactions with continuous covariates, which potentially operate in a nonlinear fashion, provide software for replicating our procedure, and discuss different approaches to deriving CIs. The presented approach will allow clinical and public health researchers to assess complex relationships between multiple covariates as they relate to a clinical endpoint, and to provide a more intuitive and precise depiction of the results in applied research papers focusing on interaction and effect stratification.

Synergistic effects of COVID-19 pandemic and sedentary lifestyles on obesity rates among South Korean adults

Since March 2020, South Korea has implemented social distancing measures to reduce the spread of the coronavirus disease (COVID-19). These policies resulted in significant changes in the lifestyle of Korean adults, including spending more time indoors and experiencing increased sedentary time during the pandemic. This study aimed to investigate the combined influence of sedentary lifestyle and the COVID-19 pandemic on obesity rates among adults residing in South Korea. Data were obtained from the 2018-2020 Korea National Health and Nutrition Examination Survey (KNHANES). Multiple logistic regression was used to analyze the synergistic effects of a sedentary lifestyle and COVID-19 on obesity. The prevalence of sedentary lifestyles among the participants increased from 30.4% pre-COVID-19 to 36.6% during the pandemic. Furthermore, the obesity rates were raised independently by COVID-19 (OR: 1.16, 95% CI 1.04-1.30) and by a sedentary lifestyle (OR = 1.17, 95% CI 1.04-1.31). A synergistic effect of a sedentary lifestyle and COVID-19 on obesity was identified (OR: 1.57, 95% CI 1.30-1.85). COVID-19 and a sedentary lifestyle significantly increased the risk of obesity in South Korean adults. Moreover, the combined synergistic effects of these risk factors were too substantial to be disregarded by merely summing their individual effects on obesity.

Incidence of and risk factors for small vulnerable newborns in north India: a secondary analysis of a prospective pregnancy cohort

BACKGROUND

Globally, recent estimates have shown there have been 3·6 million stillbirths and neonatal deaths in 2022, with nearly 60% occurring in low-income and middle-income countries. The Small Vulnerable Newborn Consortium has proposed a framework combining preterm birth (<37 weeks of gestation), small for gestational age (SGA) by INTERGROWTH-21st standard, and low birthweight (<2500 g) under the category small vulnerable newborns (SVN). Reliable data on SVN from sub-Saharan Africa, central Asia, and south Asia are sparse. We aimed to estimate the incidence of SVN and its types, and quantify risk factors, both overall and trimester-specific, from a pregnancy cohort in north India.

METHODS

In the GARBH-Ini (Interdisciplinary Group for Advanced Research on Birth Outcomes-DBT India Initiative) pregnancy cohort, 8000 participants were enrolled with less than 20 weeks' gestation between May 11, 2015, and Aug 8, 2020, at a secondary-care hospital in north India. The cohort was followed up across the antenatal period for a detailed study on preterm birth. We conducted a secondary analysis of cohort data for the outcome of SVN, classified into its types: preterm-SGA, preterm-nonSGA, and term-SGA. We estimated the relative risk and population attributable fraction of candidate risk factors for SVN (modified Poisson regression) and its types (multinomial regression).

FINDINGS

7183 (89·9%) of 7990 participants completed the study. Among 6206 newborns included for analysis, the incidence of SVN was 48·4% (35·1% term-SGA newborns [n=2179], 9·7% preterm-nonSGA newborns [n=605], and 3·6% preterm-SGA newborns [n=222]). Compared with term-nonSGA newborns, proportions of stillbirths and neonatal deaths within 72 h of birth among SVN were three times and 2·5 times higher, respectively. Preterm-SGA newborns had the highest incidence of stillbirth (15 [6·8%] of 222) and neonatal deaths (six [4·2%] of 142). Low body-mass index (BMI <18·5 kg/m2) of participants at the start of pregnancy was associated with higher risk for preterm-SGA (adjusted relative risk [RR] 1·61 [95% CI 1·17-2·22]), preterm-nonSGA (1·35 [1·09-1·68]), and term-SGA (1·44 [1·27- 1·64]), with population attributable fraction ranging from 8·7% to 13·8%. Pre-eclampsia (adjusted RR 1·48 [95% CI 1·30-1·71]), short cervical length (1·15 [1·04-1·26]), and bacterial vaginosis (1·13 [0·88-1·45]) were other important antenatal risk factors.

INTERPRETATION

In a comprehensive analysis of SVN and its types from north India, we identified risk factors to guide prioritisation of interventions. Complemented with risk-stratification tools, this focused approach will enhance antenatal care, and accelerate achievement of Sustainable Development Goals-namely, to end preventable deaths of newborns and children younger than 5 years by 2030 (target 3·2).

FUNDING

Department of Biotechnology, Government of India and Grand Challenges India-Biotechnology Industry Research Assistance Council, Government of India.

TRANSLATION

For the Hindi translation of the abstract see Supplementary Materials section.

Racial and Ethnic Disparities in Providing Guideline-Concordant Care After Hip Fracture Surgery

Importance

Institutions have adopted protocol-driven standardized hip fracture programs (SHFPs). However, concerns persist regarding bias in adherence to guideline-concordant care leading to disparities in implementing high-quality care for patients recovering from surgery for hip fracture.

Objective

To assess disparities in the implementation of guideline-concordant care for patients after hip fracture surgery in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Targeted Hip Fracture (THF) Database.

Design, Setting, and Participants

This cross-sectional study was conducted using the ACS-NSQIP THF database from 2016 to 2021 for patients aged 65 years and older with hip fractures undergoing surgical fixation. Care outcomes of racial and ethnic minority patients (including American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Pacific Islander, or multiple races and Hispanic ethnicity) were compared with non-Hispanic White patients via risk difference, stratified by care institution SHFP status. Modified Poisson regression was used to measure interactions. Statistical analysis was performed from November 2022 to June 2024.

Main Outcomes and Measures

The primary outcomes of interest encompassed weight-bearing as tolerated (WBAT) on postoperative day 1 (POD1), venous thromboembolism (VTE) prophylaxis, bone-protective medication, and the presence of SHFP at the institution.

Results

Among 62 194 patients (mean [SD] age, 82.4 [7.3] years; 43 356 [69.7%] female) who met inclusion criteria and after multiple imputation, 11.2% (95% CI, 10.8%-11.5%) were racial and ethnic minority patients, 3.3% (95% CI, 3.1%-3.4%) were Hispanic patients, and 92.0% (95% CI, 91.7%-92.2%) were White. Receiving care at an institution with an SHFP was associated with improved likelihood of receiving guideline-concordant care for all patients to varying degrees across care outcomes. SHFP was associated with higher probability of being WBAT-POD1 (risk difference for racial and ethnic minority patients, 0.030 [95% CI, 0.004-0.056]; risk difference for non-Hispanic White patients, 0.037 [95% CI, 0.029-0.45]) and being prescribed VTE prophylaxis (risk difference for racial and ethnic minority patients, 0.066 [95% CI, 0.040-0.093]; risk difference for non-Hispanic White patients, 0.080 [95% CI, 0.071-0.089]), but SHFP was associated with the largest improvements in receipt of bone-protective medications (risk difference for racial and ethnic minority patients, 0.149 [95% CI, 0.121-0.178]; risk difference for non-Hispanic White patients, 0.181 [95% CI, 0.173-0.190]). While receiving care at an SHFP was associated with improved probability of receiving guideline-concordant care in both race and ethnicity groups, greater improvements were seen among non-Hispanic White patients compared with racial and ethnic minority patients.

Conclusions and Relevance

Older adults who received care at an institution with an SHFP were more likely to receive guideline-concordant care (bone-protective medication, WBAT-POD1, and VTE prophylaxis), regardless of race and ethnicity. However, the probability of receiving guideline-concordant care at an institution with an SHFP increased more for non-Hispanic White patients than racial and ethnic minority patients.

Gestational Exposure to Maternal Systemic Glucocorticoids and Childhood Risk of CKD

RATIONALE & OBJECTIVE

The potential effects of antenatal glucocorticoid exposure on the health of children are unclear. We examined the association of gestational exposure to maternal systemic glucocorticoids and the risk of developing chronic kidney disease (CKD) in childhood.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Newborns cared for at the largest health care delivery system in Taiwan between 2004 and 2018.

EXPOSURE

Maternal prescriptions for systemic glucocorticoids between the last menstrual period and birth as a proxy for gestational exposure.

OUTCOME

Incidence of childhood CKD, including congenital anomalies of the kidney and urinary tract (CAKUT) and other kidney diseases (non-CAKUT), over 10 years.

ANALYTICAL APPROACH

Cox proportional hazards models with stabilized inverse probability of treatment weighting and robust sandwich estimator were used to estimate the average association between systemic glucocorticoids and incident CKD after adjustment for offspring characteristics (adjusted HR: AHR).

RESULTS

Among 23,363 singleton-born children, gestational systemic glucocorticoid exposure was significantly associated with a higher risk of childhood CKD (AHR, 1.69 [95% CI, 1.01-2.84]). Stratified analyses showed stronger associations between systemic glucocorticoids and childhood CKD within the strata of birth<37 weeks' gestational age (AHR, 2.38 [95% CI, 1.19-4.78]), male sex (AHR, 1.89 [95% CI, 1.00-3.55]), gestational exposure in the second trimester (AHR, 6.70 [95% CI, 2.17-20.64]), and total dose of>24mg hydrocortisone equivalent (AHR, 1.91 [95% CI, 1.05-3.47]).

LIMITATIONS

Study was limited to the Taiwan health care delivery system and childhood CKD events through the age of 10 years.

CONCLUSIONS

The findings of this study suggest that gestational exposure to systemic glucocorticoids is associated with the occurrence of kidney disease in childhood. If these findings are confirmed, they may inform clinicians who are considering prescribing systemic glucocorticoids during pregnancy.

PLAIN-LANGUAGE SUMMARY

In a singleton-born cohort of neonates, maternal exposure to antenatal systemic glucocorticoids was significantly associated with a 1.7-fold increased risk of the children developing chronic kidney disease over the first 10 years of life. Children of mothers who received>24mg of hydrocortisone equivalent, systemic glucocorticoid treatment in second trimester of gestation, and children born at<37 weeks of gestational age had a higher risk of childhood kidney disease after gestational systemic glucocorticoid exposure. If these findings are confirmed, they may inform clinicians who are considering prescribing systemic glucocorticoids during pregnancy.

The interaction of genetics and physical activity in the pathogenesis of metabolic dysfunction associated liver disease

Genetic variants associated with increased liver fat and volume have been reported, but whether physical activity (PA) can attenuate the impact of genetic susceptibility to these traits is poorly understood. We aimed to investigate whether higher PA modify genetic impact on liver-related traits in the UK Biobank cohort. PA was self-reported, while magnetic resonance images were used to estimate liver fat (n = 27,243) and liver volume (n = 24,752). Metabolic dysfunction-associated liver disease (MASLD) and chronic liver disease (CLD) were diagnosed using ICD-9 and ICD-10 codes. Ten liver fat and eleven liver volume-associated genetic variants were selected and unweighted genetic-risk scores for liver fat (GRSLF) and liver volume (GRSLV) were computed. Linear regression analyses were performed to explore interactions between GRSLF/ GRSLV and PA in relation to liver-related traits. Association between GRSLF and liver fat was not different among lower (β = 0.063, 95% CI 0.041-0.084) versus higher PA individuals (β = 0.065, 95% CI 0.054-0.077, pinteraction = 0.62). The association between the GRSLV and liver volume was not different across different PA groups (pinteraction = 0.71). Similarly, PA did not modify the effect of GRSLF and GRSLV on MASLD or CLD. Our findings show that physical activity and genetic susceptibility to liver-related phenotypes seem to act independently, benefiting all individuals regardless of genetic risk.

Guide to Decomposition of Causal Effects Into Mediation, Interaction, and Direct Effects: Case Study on Aerobic Exercise and Parkinson Disease

Mediation analysis can be applied in medical research with the aim of understanding the pathways that operate between an exposure and its effects on an outcome. This method can help to improve our understanding of pathophysiologic mechanisms and may guide the choice of potential treatment strategies. Traditional mediation analysis decomposes the total effect of an intervention on the outcome into 2 effects: (1) an indirect effect, from exposure using a mediator to the outcome, and (2) a direct effect, directly from exposure to outcome. A limitation of this method is that it assumes no interaction between the exposure and the mediator, which can either lead to an over- or underestimation of clinically relevant effects. The "4-way decomposition" method has the advantage of overcoming this limitation. Specifically, the total effect of an exposure on the outcome is decomposed into 4 elements: (1) reference interaction (interaction only), (2) mediated interaction (mediation and interaction), (3) the pure indirect effect (mediation but not interaction), and (4) the direct effect (no mediation and no interaction). We provide a guide to select the most appropriate method to investigate and decompose any causal effect given the research question at hand. We explain the application of the 4-way decomposition and illustrate this with a real-world example of how aerobic exercise may influence motor function in persons with Parkinson disease.

Racial and ethnic minority status in country of birth modifies racial and ethnic disparities in influenza vaccination among New York City adults

BACKGROUND

Understanding the relationship between race/ethnicity, birthplace, and health outcomes is important for reducing health disparities. This study assessed the relationship between racial/ethnic identity and minority racial/ethnic status in country of birth on influenza vaccination among New York City (NYC) adults.

METHODS

Using 2015-2019 data from NYC's Community Health Surveys, we assessed the association between racial/ethnic identity and racial/ethnic minority status in birth country with past year influenza vaccination, calculating prevalence differences per 100 and assessing interaction on the additive scale using linear binomial regression, and prevalence ratios and interaction on the multiplicative scale using log-binomial regression.

RESULTS

Effect modification between race/ethnicity and minority racial/ethnic status in birth country was significant on the additive scale for Hispanic (p = 0.018) and Black (p = 0.025) adults and the multiplicative scale for Hispanic adults (p = 0.040). After stratifying by racial/ethnic minority or majority status in birth country, vaccination was significantly lower among Black adults compared with White adults among those in the minority (adjusted prevalence difference [aPD]=-12.98, 95%CI: -22.88-(-2.92)) and significantly higher among Hispanic adults compared with White adults among those in the majority (aPD=9.28, 95%CI: 7.35-11.21).

CONCLUSIONS

Racial/ethnic minority status in birth country is an important factor when examining racial/ethnic differences in vaccination status.

Emotion regulation as a potential moderator of the association between HIV stigma and nonadherence to antiretroviral therapy among youth living with HIV

INTRODUCTION

Human immunodeficiency virus (HIV)-related stigma affects adherence to antiretroviral therapy (ART) for youth living with HIV. Emotion regulation strategies such as cognitive reappraisal (reinterpreting adversity to mitigate emotional impact) and expressive suppression (inhibiting emotion-expressive behavior activated by adversity) may moderate the HIV stigma-ART adherence relationship in this group.

METHODS

Using baseline data from 208 youth living with HIV aged 15-24 years enrolled in an mHealth ART-adherence intervention, we performed modified Poisson regressions with robust variance between HIV stigma (internalized, anticipated, enacted) and ART nonadherence. We tested for multiplicative interaction via product terms between HIV stigma and emotion regulation scores, and additive interaction via relative excess risk due to interaction and attributable proportion using dichotomous HIV stigma and emotion regulation variables.

RESULTS

Mean age was 21 years; ≥50% of participants were cisgender male, non-Hispanic Black, and gay-identifying; 18% reported ART nonadherence. Confounder-adjusted regressions showed positive associations between each HIV stigma variable and ART nonadherence. Internalized HIV stigma and cognitive reappraisal negatively, multiplicatively interacted (as internalized HIV stigma increased, ART nonadherence increased for those with low cognitive reappraisal). High internalized HIV stigma positively, additively interacted with low cognitive reappraisal and low expressive suppression (when high internalized HIV stigma and low levels of either emotion regulation strategy were present, ART nonadherence increased dramatically).

CONCLUSION

Cognitive reappraisal and expressive suppression may protect against internalized HIV stigma's harmful association with ART nonadherence. These modifiable emotion regulation strategies may be targeted to potentially buffer the effects of internalized HIV stigma and support ART adherence for youth living with HIV.

Reporting and Description of Research Methodology in Studies Estimating Effects of Firearm Policies

BACKGROUND

Evidence about which firearm policies work, to what extent, and for whom is hotly debated, perhaps partly because variation in research methodology has produced mixed and inconclusive effect estimates. We conducted a scoping review of firearm policy research in the health sciences in the United States, focusing on methodological considerations for causal inference.

METHODS

We identified original, empirical articles indexed in PubMed from 1 January 2000 to 1 September 2021 that examined any of 18 prespecified firearm policies. We extracted key study components, including policy type(s) examined, policy operationalization, outcomes, study setting and population, study approach and design, causal language, and whether and how authors acknowledged potential sources of bias.

RESULTS

We screened 7733 articles and included 124. A plurality of studies used a legislative score as their primary exposure (n = 39; 32%) and did not examine change in policies over time (n = 47; 38%). Most examined firearm homicide (n = 51; 41%) or firearm suicide (n = 40; 32%) as outcomes. One-third adjusted for other firearm policies (n = 41; 33%). Three studies (2%) explicitly mentioned that their goal was to estimate causal effects, but over half used language implying causality (n = 72; 58%). Most acknowledged causal identification assumptions of temporality (n = 91; 73%) and exchangeability (n = 111; 90%); other assumptions were less often acknowledged. One-third of studies included bias analyses (n = 42; 34%).

CONCLUSIONS

We identified a range of methodologic approaches in firearm policy research in the health sciences. Acknowledging the imitations of data availability and quality, we identify opportunities to improve causal inferences about and reporting on the effects of firearm policies on population health.

Prevalence, correlates, and mental health outcomes of social jetlag in Chinese school-age adolescents: A large-scale population-based study

BACKGROUND

This cross-sectional study aimed to examine the prevalence and correlates of social jetlag (SJL) in Chinese adolescents, as well as to test the relationships between SJL and mental health problems.

METHODS

A total of 106979 students (Mage = 13.0 ± 1.8 years; Nmale = 58296 [54.5 %]) from Shenzhen, China completed an online survey from May 24th to June 5th, 2022. Information on sociodemographics, lifestyles, sleep characteristics, anxiety symptoms, and depressive symptoms was collected by a self-administered questionnaire. Multivariate and binary logistic regression were adopted for data analysis.

RESULTS

17.8 % of participants experienced SJL ≥ 2 h. To adjust the accumulated sleep debt, sleep-corrected SJL (SJLsc) was calculated and 8.3 % of individuals self-reported SJLsc ≥ 2 h. Both SJL and SJLsc show an increasing trend with age. Risk factors of SJL included females, poor parental marital status, being overweight, physically inactive, smoking, drinking, and having a late chronotype. Moreover, males, having siblings, boarding at school, short sleep duration, experiencing insomnia, and frequent nightmares were significantly associated with an increased risk of SJLsc. After adjusting for all covariates, adolescents with SJLsc ≥ 2 h were more likely to have anxiety symptoms (OR: 1.35, 95 % CI: 1.24-1.48) and depressive symptoms (OR: 1.35, 95 % CI: 1.25-1.46) than those with SJLsc < 1 h.

CONCLUSIONS

SJL is common among Chinese school-age adolescents. This study is valuable for the development of prevention and intervention strategies for SJL in adolescents at the population level. Additionally, the strong links between SJLsc and emotional problems underscore the critical significance of addressing SJL as a key aspect of adolescent well-being.

Assessing Additive Interactions between Protective Factors Using Relative Risk Reduction Due to Interaction

Background and Objectives: In the context of disease prevention, interaction on an additive scale is commonly assessed to determine synergistic effects between exposures. While the "Relative Excess Risk due to Interaction" represents the main measure of additive interaction between risk factors, in this study we aimed to extend this approach to assess additive interaction between factors known to prevent the event's occurrence, such as medical interventions and drugs. Materials and Methods: We introduced and described the "Relative Risk Reduction due to Interaction" (RRRI) as a key measure to assess additive interactions between preventive factors, such as therapeutic interventions and drug combinations. For RRRI values closer to 1, the combination of exposures has a greater impact on reducing the event risk due to their interaction. As a purely illustrative example, we re-evaluated a previous investigation of the synergistic effect between statins and blood pressure-lowering drugs in preventing major adverse cardiovascular events (MACE). Moreover, simulation studies were used to empirically evaluate the performance of a robust Poisson regression model to estimate RRRI across different scenarios. Results: In our example, the drug combination revealed a positive additive interaction in further reducing MACE risk (RRRI > 0), even if not statistically significant. This result is more straightforward to interpret as compared to the original one based on the RERI. Additionally, our simulations highlighted the importance of large sample sizes for detecting significant interaction effects. Conclusion: We recommend RRRI as the main measure to be considered when exploring additive interaction effects between protective exposures, such as the investigation of synergistic effects between drug combinations or preventive treatments.

The Association between Autism Spectrum Disorder and Precocious Puberty: Considering Effect Modification by Sex and Neuropsychiatric Comorbidities

Limited knowledge is available about the association between autistic spectrum disorder (ASD) and precocious puberty. Our study examined the association between the two medical conditions and effect modification by sex and neuropsychiatric comorbidities in a nationwide population. To compare the risk of precocious puberty between ASD and non-ASD cases, we conducted a Cox regression analysis using ASD as the exposure and time to precocious puberty as the outcome. We adjusted for sex, attention-deficit/hyperactivity disorder (ADHD), tic disorder, obsessive-compulsive disorder (OCD), anxiety disorder, intellectual disability, and epilepsy. We performed a moderation analysis to examine the potential moderating effects of sex and comorbidities. Patients with ASD were prone to have precocious puberty, with an adjusted hazard ratio (aHR) of 1.80 (95% CI: 1.61-2.01). For effect modification, sex, specifically females, moderated the association between ASD and precocious puberty, with a relative excess risk due to interaction (RERI) of 7.35 (95% CI 4.90-9.80). No significant effect modification was found for any of the comorbidities within the scope of additive effect modification. We found that patients with ASD were prone to precocious puberty, regardless of sex or comorbid neuropsychiatric disorders. Girls with ASD are at a particularly higher risk of developing precocious puberty.

Effects of Coexposure to Air Pollution from Vegetation Fires and Extreme Heat on Mortality in Upper Northern Thailand

Background: understanding the effects of coexposure to compound extreme events, such as air pollution and extreme heat, is important for reducing current and future health burdens. This study investigated the independent and synergistic effects of exposure to air pollution from vegetation fires and extreme heat on all-cause mortality in Upper Northern Thailand. Methods: we used a time-stratified case-crossover study design with a conditional quasi-Poisson model to examine the association between mortality and coexposure to air pollution due to vegetation fire events (fire-PM2.5) and extreme heat. Extreme heat days were defined using the 90th and 99th percentile thresholds for daily maximum temperature. Results: we observed a significant positive excess risk of mortality due to independent exposure to fire-PM2.5 and extreme heat, but not an interactive effect. All-cause mortality risk increased by 0.9% (95% confidence interval (CI): 0.1, 1.8) for each 10 μg/m3 increase in fire-PM2.5 on the same day and by 12.8% (95% CI: 10.5, 15.1) on extreme heat days (90th percentile) relative to nonextreme heat days. Conclusion: this study showed that exposure to PM2.5 from vegetation fires and extreme heat independently increased all-cause mortality risk in UNT. However, there was no evidence of a synergistic effect of these events.

Causal Inference About the Effects of Interventions From Observational Studies in Medical Journals

Importance

Many medical journals, including JAMA, restrict the use of causal language to the reporting of randomized clinical trials. Although well-conducted randomized clinical trials remain the preferred approach for answering causal questions, methods for observational studies have advanced such that causal interpretations of the results of well-conducted observational studies may be possible when strong assumptions hold. Furthermore, observational studies may be the only practical source of information for answering some questions about the causal effects of medical or policy interventions, can support the study of interventions in populations and settings that reflect practice, and can help identify interventions for further experimental investigation. Identifying opportunities for the appropriate use of causal language when describing observational studies is important for communication in medical journals.

Observations

A structured approach to whether and how causal language may be used when describing observational studies would enhance the communication of research goals, support the assessment of assumptions and design and analytic choices, and allow for more clear and accurate interpretation of results. Building on the extensive literature on causal inference across diverse disciplines, we suggest a framework for observational studies that aim to provide evidence about the causal effects of interventions based on 6 core questions: what is the causal question; what quantity would, if known, answer the causal question; what is the study design; what causal assumptions are being made; how can the observed data be used to answer the causal question in principle and in practice; and is a causal interpretation of the analyses tenable?

Conclusions and Relevance

Adoption of the proposed framework to identify when causal interpretation is appropriate in observational studies promises to facilitate better communication between authors, reviewers, editors, and readers. Practical implementation will require cooperation between editors, authors, and reviewers to operationalize the framework and evaluate its effect on the reporting of empirical research.

Harnessing causal forests for epidemiologic research: key considerations

Assessing heterogeneous treatment effects (HTEs) is an essential task in epidemiology. The recent integration of machine learning into causal inference has provided a new, flexible tool for evaluating complex HTEs: causal forest. In a recent paper, Jawadekar et al (Am J Epidemiol. 2023;192(7):1155-1165) introduced this innovative approach and offered practical guidelines for applied users. Building on their work, this commentary provides additional insights and guidance to promote the understanding and application of causal forest in epidemiologic research. We start with conceptual clarifications, differentiating between honesty and cross-fitting, and exploring the interpretation of estimated conditional average treatment effects. We then delve into practical considerations not addressed by Jawadekar et al, including motivations for estimating HTEs, calibration approaches, and ways to leverage causal forest output with examples from simulated data. We conclude by outlining challenges to consider for future advancements and applications of causal forest in epidemiologic research.

Association of Problematic Internet Use With Psychotic Experiences and Depression in Adolescents: A Cohort Study

BACKGROUND AND HYPOTHESIS

Problematic internet use (PIU) is prevalent among adolescents. Past research suggested cross-sectional associations between PIU and psychotic experiences, but little information is available on the longitudinal association. We hypothesized that PIU in adolescence may be longitudinally associated with psychotic experiences, adjusting for confounders.

STUDY DESIGN

We analyzed a random sample of adolescents in the Tokyo Teen Cohort to examine how PIU at ages 10 (2012-2015), 12 (2014-2017), and 16 (2019-2021) was associated with mental health issues at age 16. PIU was evaluated by the modified Compulsive Internet Use Scale, psychotic experiences by the Adolescent Psychotic-like Symptom Screener, and depression by the Short Mood and Feelings Questionnaire. We also examined the mediating role of social withdrawal.

STUDY RESULTS

We analyzed 3171 adolescents; 151 reported psychotic experiences and 327 reported depression at age 16. Compared with the lowest tertile PIU group, the highest tertile PIU group at age 12 showed an increased adjusted risk of psychotic experiences (RD 3.3%, 95% CI 2.9%-3.7%; RR 1.65, 95% CI 1.55-1.73) and depression (RD 5.9%, 95% CI 5.5%-6.3%; RR 1.61, 95% CI 1.55-1.68) at age 16. PIU at age 16 showed analogous results, while PIU at age 10 suggested a smaller impact. Social withdrawal mediated 9.4%-29.0% of the association between PIU and psychotic experiences.

CONCLUSIONS

PIU is longitudinally associated with psychotic experiences and depression in adolescents. Further longitudinal and intervention studies are warranted to provide robust public health implications and foster a safer digital future.

Causal Inference Challenges in the Relationship Between Social Determinants and Cardiovascular Outcomes

The effects of social determinants on cardiovascular outcomes are frequently estimated in epidemiologic analyses, but the profound causal and statistical challenges of this research program are not widely discussed. Here, we carefully review definitions and measures for social determinants of cardiovascular health and then examine the various assumptions required for valid causal inference in multivariable analyses of observational data, such as what one would typically encounter in cohorts, population surveys, health care databases, and vital statistics databases. We explain the necessity of the "well-defined exposure" and show how this goal relates to the "consistency assumption" that is necessary for valid causal inference. Well-defined exposure is especially challenging for social determinants of health because they are seldom simple atomistic interventions that are easily conceptualized and measured. We then review threats to valid inference that arise from confounding, selection bias, information bias, and positivity violations. Other causal considerations are reviewed and explained, such as correct model specification, absence of immortal time, and avoidance of the "Table 2 Fallacy," and their application to social determinants of cardiovascular outcomes are discussed. Fruitful approaches, including focusing on policy interventions and the "target trial" frameworks are proposed and provide a pathway for a more efficacious research program that can more reliably improve population health. Valid causal inference in this setting is quite challenging, but-with clever design and thoughtful analysis-the important role of social factors in patterning cardiovascular outcomes can be quantified and reported.

Metabolic profiling of smoking, associations with type 2 diabetes and interaction with genetic susceptibility

BACKGROUND

Smokers are at increased risk of type 2 diabetes (T2D), but the underlying mechanisms are unclear. We investigated if the smoking-T2D association is mediated by alterations in the metabolome and assessed potential interaction with genetic susceptibility to diabetes or insulin resistance.

METHODS

In UK Biobank (n = 93,722), cross-sectional analyses identified 208 metabolites associated with smoking, of which 131 were confirmed in Mendelian Randomization analyses, including glycoprotein acetyls, fatty acids, and lipids. Elastic net regression was applied to create a smoking-related metabolic signature. We estimated hazard ratios (HR) of incident T2D in relation to baseline smoking/metabolic signature and calculated the proportion of the smoking-T2D association mediated by the signature. Additive interaction between the signature and genetic risk scores for T2D (GRS-T2D) and insulin resistance (GRS-IR) on incidence of T2D was assessed as relative excess risk due to interaction (RERI).

FINDINGS

The HR of T2D was 1·73 (95% confidence interval (CI) 1·54 - 1·94) for current versus never smoking, and 38·3% of the excess risk was mediated by the metabolic signature. The metabolic signature and its mediation role were replicated in TwinGene. The metabolic signature was associated with T2D (HR: 1·61, CI 1·46 - 1·77 for values above vs. below median), with evidence of interaction with GRS-T2D (RERI: 0·81, CI: 0·23 - 1·38) and GRS-IR (RERI 0·47, CI: 0·02 - 0·92).

INTERPRETATION

The increased risk of T2D in smokers may be mediated through effects on the metabolome, and the influence of such metabolic alterations on diabetes risk may be amplified in individuals with genetic susceptibility to T2D or insulin resistance.

The clustering effects of current smoking status, overweight/obesity, and physical inactivity with all-cause and cause-specific mortality risks in U.S. adults

Objective

To estimate the associations of smoking, weight status and physical inactivity with all-cause and cause-specific deaths, and the advanced rate period (RAP) to determine how early death was advanced among United States (U.S.) adults aged 18 years or older.

Methods

We used data from the third National Health and Nutrition Examination Survey (NHANES III) and the 2019 Linked Mortality File (LMF) with a follow-up period of 21.6 years (n = 16,612, including 7,278 deaths). Smoking, weight status, and physical inactivity were obtained from NHANES III and mortality outcomes from the 2019 LMF. Cox regression was used to estimate hazard ratios, RAPs and their corresponding confidence intervals.

Results

For adults who currently smoke, were obese and physically inactive, the rate of dying from all-cause, CVD, and cancer was at least 231 % greater than for those who never smoked, were normal weight and physically active. The RAPs associated with the clustering of these risk factors for all cause, CVD- and cancer-specific cause of deaths were 13.0, 12.1 and 18.9 years older, respectively.

Conclusions

Our findings underscore the need to focus on modifiable risk factors for illness prevention and health promotion and call attention to the increasing clustering of unhealthy risk factors in the U.S. population.

Use of melatonin supplements and risk of type 2 diabetes and cardiovascular diseases in the USA: insights from three prospective cohort studies

BACKGROUND

Use of melatonin supplements has been increasing substantially in both children and adults in the USA; however, their long-term cardiometabolic effects remain unclear. We aimed to assess the associations between regular use of melatonin supplements and the risk of developing type 2 diabetes or cardiovascular disease in adults.

METHODS

In this study, we included individuals from three US cohorts: the Nurses' Health Study (women only), the Health Professionals Follow-up Study (men only), and the Nurses' Health Study II (women only). Women aged 25-55 years and men aged 45-75 years at baseline, who had no diagnosis of cancer at baseline, and who responded to the question about melatonin supplement use (yes or no) were included. We excluded baseline prevalent cardiovascular disease and baseline prevalent type 2 diabetes for the main analyses. The main outcomes were cardiovascular disease and type 2 diabetes incidence. In secondary analyses, we stratified by duration of rotating night shift work in the Nurses' Health Study and Nurses' Health Study II to examine whether the associations with melatonin supplement use differed by rotating night shift work.

FINDINGS

For the cardiovascular disease analysis, we included 67 202 women from the Nurses' Health Study (follow-up 1998-2019, mean age at baseline: 63·6 years [SD 7·1]), 26 629 men from the Health Professionals Follow-up Study (1998-2020, 62·9 years [8·8], and 65 241 women from the Nurses' Health Study II (2003-19, 48·2 years [4·7]). Follow-up for incident type 2 diabetes was from 1998 to June 30, 2021, for the Nurses' Health Study; 2003 to Jan 31, 2023, for the Nurses' Health Study II; and from 1998 to Jan 31, 2020, for the Health Professionals' Follow-up Study. Melatonin supplement use in the study cohorts doubled over recent decades from less than 2% in 1998-2007 to 4% or higher in 2014-15 (4·0% in men and 5·3% in women). We documented 16 917 incident cardiovascular disease events during 2 609 068 person-years of follow-up and 12 730 incident cases of type 2 diabetes during 2 701 830 person-years of follow-up. In a pooled analysis of the three cohorts, comparing users with non-users of melatonin supplements, the pooled multivariable-adjusted hazard ratios were 0·94 (95% CI 0·83-1·06, p=0·32) for cardiovascular disease and 0·98 (0·86-1·12, p=0·80) for type 2 diabetes. In secondary analyses, melatonin supplement use appeared to attenuate the positive association between long-term shift work (>5 years) and risk of cardiovascular disease (pinteraction=0·013) among the female nurses.

INTERPRETATION

With up to 23 years of follow-up of three large prospective cohorts of middle-aged and older men and women, self-reported melatonin supplement use was not associated with risk of type 2 diabetes or cardiovascular disease. Further research is warranted to assess if melatonin supplement use could mitigate the potential risks of type 2 diabetes and cardiovascular disease associated with rotating night shift work.

FUNDING

US National Institutes of Health.

Do dental anxiety and satisfaction with dental professionals modify the association between affordability and dental service use? A population-based longitudinal study of Australian adults

OBJECTIVES

This study aimed to assess the association between affordability in terms of difficulty paying dental bills in Australian dollars and dental service use in the presence of sociodemographic confounders, and to assess the role of dental anxiety and satisfaction with dental professionals as mediators. The second aim was to investigate how dental anxiety and satisfaction with dental professionals modify the association between affordability and use of dental services in Australian adults.

METHODS

Longitudinal data from the Australian National Study of Adult Oral Health (2004-06 and 2017-18) was used. Poisson regression and path analysis were conducted to determine the association between affordability and frequency of use of dental services. Effect measure modification (EMM) analysis was performed by stratification of dental anxiety and satisfaction with dental professionals.

RESULTS

The study included 1698 Australian adults and identified that the prevalence of low frequency of dental visits was 20% more for those who had difficulty paying dental bills. Adults with dental anxiety (prevalence ratio [PR] = 1.14) and those who were dissatisfied with dental professionals (PR = 1.17) had a higher prevalence of low frequency of dental visits in the presence of difficulty paying dental bills. This indicated that dental anxiety and dissatisfaction with dental professionals were effect modifiers on this pathway.

CONCLUSIONS

Adults who experience dental anxiety and dissatisfaction with dental professionals are more likely to avoid dental visits when faced with difficulty paying dental bills. However, it is important to note that these associations do not necessarily imply a causal relationship.

Associations of Lifestyle and Genetic Risks with Obesity and Related Chronic Diseases in the UK Biobank: A Prospective Cohort Study

BACKGROUND

Interplay between lifestyle risk scores (LRSs) and genetic risk scores (GRSs) on obesity and related chronic diseases are underinvestigated and necessary for understanding obesity causes and developing prevention strategies.

OBJECTIVES

This study aimed to investigate independent and joint associations and interactions of LRS and GRS with obesity prevalence and risks of diabetes, cardiovascular disease (CVD), and obesity-related cancer.

METHODS

In this cohort study of 444,957 UK Biobank participants [age: 56.5 ± 8.1 y; BMI (in kg/m2): 27.4 ± 4.7], LRS included physical activity, dietary score, sedentary behavior, sleep duration, and smoking (range: 0-20, each factor had 5 levels). GRS was calculated based on 941 genetic variants related to BMI. Both scores were categorized into quintiles. Obesity (n = 106,301) was defined as baseline BMI ≥30. Incident diabetes (n = 16,311), CVD (n = 18,076), and obesity-related cancer (n = 17,325) were ascertained through linkage to registries over a median of 12-y follow-up.

RESULTS

The LRS and GRS were independently positively associated with all outcomes. Additive interactions of LRS and GRS were observed for all outcomes (P < 0.021). Comparing the top with bottom LRS quintile, prevalence differences (95% CIs) for obesity were 17.8% (15.9%, 19.7%) in the top GRS quintile and 10.7% (8.3%, 13.1%) in the bottom GRS quintile; for diabetes, CVD, and obesity-related cancer, incidence rate differences associated with per SD increase in LRS were greater in the top than that in the bottom GRS quintile. Participants from top quintiles of both LRS and GRS had 6.16-fold, 3.81-fold, 1.56-fold, and 1.44-fold higher odds/risks of obesity, diabetes, CVD, and obesity-related cancer, respectively, than those from bottom quintiles of both scores.

CONCLUSIONS

Higher LRS was associated with higher obesity prevalence and risks of related chronic diseases regardless of GRS, highlighting the broad benefits of healthy lifestyles. Additive gene-lifestyle interactions emphasize the public health importance of lifestyle interventions among people with high genetic risks.

Differences in metabolomic profiles between Black and White women in the U.S.: Analyses from two prospective cohorts

There is growing interest in incorporating metabolomics into public health practice. However, Black women are under-represented in many metabolomics studies. If metabolomic profiles differ between Black and White women, this under-representation may exacerbate existing Black-White health disparities. We therefore aimed to estimate metabolomic differences between Black and White women in the U.S. We leveraged data from two prospective cohorts: the Nurses' Health Study (NHS; n = 2077) and Women's Health Initiative (WHI; n = 2128). The WHI served as the replication cohort. Plasma metabolites (n = 334) were measured via liquid chromatography-tandem mass spectrometry. Observed metabolomic differences were estimated using linear regression and metabolite set enrichment analyses. Residual metabolomic differences in a hypothetical population in which the distributions of 14 risk factors were equalized across racial groups were estimated using inverse odds ratio weighting. In the NHS, Black-White differences were observed for most metabolites (75 metabolites with observed differences ≥ |0.50| standard deviations). Black women had lower average levels than White women for most metabolites (e.g., for N6, N6-dimethlylysine, mean Black-White difference = - 0.98 standard deviations; 95% CI: - 1.11, - 0.84). In metabolite set enrichment analyses, Black women had lower levels of triglycerides, phosphatidylcholines, lysophosphatidylethanolamines, phosphatidylethanolamines, and organoheterocyclic compounds, but higher levels of phosphatidylethanolamine plasmalogens, phosphatidylcholine plasmalogens, cholesteryl esters, and carnitines. In a hypothetical population in which distributions of 14 risk factors were equalized, Black-White metabolomic differences persisted. Most results replicated in the WHI (88% of 272 metabolites available for replication). Substantial differences in metabolomic profiles exist between Black and White women. Future studies should prioritize racial representation.

The interaction effects of zinc and polygenic risk score with benzo[a]pyrene exposure on lung cancer risk: A prospective case-cohort study among Chinese populations

The relationship of exposure to benzo[a]pyrene (BaP) with lung cancer risk has been firmly established, but whether this association could be modified by other environmental or genetic factors remains to be explored. To investigate whether and how zinc (Zn) and genetic predisposition modify the association between BaP and lung cancer, we performed a case-cohort study with a 5.4-year median follow-up duration, comprising a representative subcohort of 1399 participants and 359 incident lung cancer cases. The baseline concentrations of benzo[a]pyrene diol epoxide-albumin adduct (BPDE-Alb) and Zn were quantified. We also genotyped the participants and computed the polygenic risk score (PRS) for lung cancer. Our findings indicated that elevated BPDE-Alb and PRS were linked to increased lung cancer risk, with the HR (95%CI) of 1.54 (1.36, 1.74) per SD increment in ln-transformed BPDE-Alb and 1.27 (1.14, 1.41) per SD increment in PRS, but high plasma Zn level was linked to a lower lung cancer risk [HR (95%CI)=0.77 (0.66, 0.91) per SD increment in ln-transformed Zn]. There was evidence of effect modification by Zn on BaP-lung cancer association (P for multiplicative interaction = 0.008). As Zn concentrations increased from the lowest to the highest tertile, the lung cancer risk per SD increment in ln-transformed BPDE-Alb decreased from 2.07 (1.48, 2.89) to 1.33 (0.90, 1.95). Additionally, we observed a significant synergistic interaction of BPDE-Alb and PRS [RERI (95%CI) = 0.85 (0.03, 1.67)], with 42% of the incident lung cancer cases among individuals with high BPDE-Alb and high PRS attributable to their additive effect [AP (95%CI) = 0.42 (0.14, 0.69)]. This study provided the first prospective epidemiological evidence that Zn has protective effect against BaP-induced lung tumorigenesis, whereas high genetic risk can enhance the harmful effect of BaP. These findings may provide novel insight into the environment-environment and environment-gene interaction underlying lung cancer development, which may help to develop prevention and intervention strategies to manage BaP-induced lung cancer.

Associations of evening-type and insomnia symptoms with depressive symptoms among youths

BACKGROUND

Evening-type and insomnia symptoms are significantly related to each other and independently associated with depressive symptoms, yet few studies have examined the potential interaction between these two conditions. Therefore, we aimed to examine the associations of evening-type and insomnia symptoms with depressive symptoms among Chinese youths, with a specific focus on the joint effects of the two conditions on depressive symptoms.

METHODS

Participants aged between 12 and 25 were invited to participate in an online survey from December 15, 2022, to May 26, 2023. Multivariate logistic regression models and additive interaction models were used to examine the independent and joint effects of chronotypes and insomnia symptoms on depressive symptoms, respectively.

RESULTS

Of the 6145 eligible youths, the prevalence of evening-type and insomnia symptoms were 24.9 % and 29.6 %, respectively. Both evening-type (adjusted OR, [AdjOR]: 3.21, 95 % CI: 2.80-3.67) and insomnia symptoms (AdjOR: 10.53, 95 % CI: 9.14-12.12) were associated with an increased risk of depressive symptoms. In addition, the additive interaction models showed that there is an enhanced risk of depression related to interaction between evening-type and insomnia symptoms (relative excess risk due to interaction, [RERI]: 11.66, 95 % CI: 7.21-16.11).

CONCLUSIONS

The present study provided additional evidence demonstrating the presence of interaction between evening-type and insomnia symptoms, which can lead to a higher risk of depressive symptoms. Our findings argue the need for addressing both sleep and circadian factors in the management of depressive symptoms in young people.

The Alcohol Harm Paradox in Periodontitis

Individuals of lower socioeconomic position (SEP) experience a greater rate of alcohol-related harms, yet they consume equal or lower amounts of alcohol than higher-SEP individuals. This phenomenon, called the "alcohol harm paradox" (AHP), gained attention recently, and different mechanisms have been proposed to explain it. Since both SEP and alcohol have been suggested to be associated with periodontitis risk, we conducted a secondary analysis using data from the National Health and Nutrition Examination Survey 2011 to 2012 and 2013 to 2014 cycles, aiming to examine 1) whether the association between alcohol consumption and periodontitis is modified by SEP and 2) the extent to which the effect of SEP inequalities on periodontitis is mediated by and/or interacts with alcohol consumption. We set educational attainment as the main SEP proxy and tested the poverty income ratio in subsequent sensitivity analyses. Effect measure modification analysis was employed, considering heavy drinking as exposure, and causal mediation analysis based on the potential outcome's framework decomposed the effect of SEP on periodontitis in proportions attributable to mediation and interaction. Models were fitted using binary logistic regression and adjusted for sex, ethnicity, age, body mass index, smoking status, diabetes, binge drinking, and regular preventive dental visits. The analytical sample comprised 4,057 participants. After adjusting for covariates, less educated heavy drinkers presented 175% (odds ratio, 2.75; 95% confidence interval [CI], 2.04-3.72) higher odds of periodontitis than their counterparts, and super-additive associations were found (relative excess risk due to interaction: 1.35; 95% CI, 0.49-2.20). Additionally, -69.5% (95% CI, -122.1% to -16.8%) of the effects of education on periodontitis were attributable to interaction with heavy drinking, consistent with the AHP. No contribution was found for the mechanism of mediation. Heavy drinking disproportionately impacts the occurrence of periodontitis in lower-SEP individuals. Lower-SEP individuals seem to experience differential effects of heavy drinking on periodontitis.

The Tryptophan Index Is Associated with Risk of Ischemic Stroke: A Community-Based Nested Case-Control Study

BACKGROUND

The relative availability of the essential amino acid tryptophan in the brain, as indicated by the tryptophan index, which is the ratio of tryptophan to its competing amino acids (CAAs) in circulation, has been related to major depression. However, it remains unknown whether tryptophan availability is involved in the pathogenesis of ischemic stroke.

AIMS

We aimed to investigate the relationship between the tryptophan index and the risk of ischemic stroke.

METHODS

We performed a nested case-control study within a community-based cohort in eastern China over the period 2013 to 2018. The analysis included 321 cases of ischemic stroke and 321 controls matched by sex and date of birth. The plasma levels of tryptophan and CAAs, including tyrosine, valine, phenylalanine, leucine, and isoleucine, were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry. Conditional logistic regression analyses were employed to determine incidence rate ratios (IRRs) and their 95% confidence intervals (CIs).

RESULTS

After adjustment for body mass index, current smoking status, educational attainment, physical activity, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate, an elevated tryptophan index was significantly associated with a reduced risk of ischemic stroke in a dose-response manner (IRR, 0.76; 95% CI, 0.63-0.93, per standard deviation increment). The plasma tryptophan or CAAs were not separately associated with the risk of ischemic stroke.

CONCLUSIONS

The tryptophan index was inversely associated with the risk of ischemic stroke. Our novel observations suggest that the availability of the essential amino acid tryptophan in the brain is involved in the pathogenesis of ischemic stroke.

Cigarette smoking and prostate cancer aggressiveness among African and European American men

PURPOSE

Smoking is a modifiable lifestyle factor that has not been established as a prostate cancer risk factor, nor emphasized in prostate cancer prevention. Studies have shown that African American (AA) smokers have a poorer cancer prognosis than European Americans (EAs), while having a lower prevalence of heavy smoking. We examined the relationship between cigarette smoking and prostate cancer aggressiveness and assessed racial differences in smoking habits on the probability of high-aggressive prostate cancer.

METHODS

Using data from the North Carolina-Louisiana Prostate Cancer Project (n = 1,279), prostate cancer aggressiveness was defined as high or low based on Gleason scores, serum prostate-specific antigen levels, and tumor stage. Cigarette smoking was categorized as current, former, or never smokers. Multivariable logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Self-reported current (OR = 1.99; 95% CI 1.30-3.06) smoking was associated with high-aggressive prostate cancer relative to never smokers. When stratified by self-reported race, the odds of having high-aggressive cancer increased among AA current (OR = 3.58; 95% CI 2.04-6.28) and former smokers (OR = 2.21; 95% CI 1.38-3.53) compared to AA never smokers, but the odds were diminished among the EA stratum (Pself-reported race x smoking status = 0.003).

CONCLUSION

Cigarette smoking is associated with prostate cancer aggressiveness, a relationship modulated by self-reported race. Future research is needed to investigate types of cigarettes smoked and metabolic differences that may be contributing to the racial disparities observed.

The effects and potential mechanisms of essential metals on the associations of polycyclic aromatic hydrocarbons with blood cell-based inflammation markers

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are well-acknowledged pro-inflammatory chemicals, but their associations with blood cell-based inflammatory biomarkers need further investigation. Moreover, the effects and mechanisms of essential metals on PAH-related inflammation remain poorly understood.

OBJECTS

To elucidate the associations of PAHs on inflammatory biomarkers, as well as the effects and mechanisms of essential metals on these associations.

METHODS

A cross-sectional study was conducted on 1388 coke oven workers. We analyzed the modification effects of key essential metal(s) on PAHs-inflammatory biomarkers associations. To explore the possible mechanisms from an inflammation perspective, we performed a bioinformatic analysis on the genes of PAHs and essential metals obtained from the Comparative Toxicogenomics Database (CTD) and performed a mediation analysis.

RESULTS

We observed associations of PAHs and essential metals with lymphocyte-to-monocyte ratio (LMR) (P < 0.05). PAH mixtures were inversely associated with LMR (βQGC-index = -0.18, P < 0.001), with 1-hydroxypyrene (1-OH-Pyr) being the most prominent contributor (weight = 63.37%), whereas a positive association between essential metal mixtures and LMR was observed (βQGC-index = 0.14, P < 0.001), with tin being the most significant contributor (weight = 51.61%). An inverse association of 1-OH-Pyr with LMR was weakened by increased tin exposure (P < 0.05). The CTD database showed that PAHs and tin compounds co-regulated 22 inflammation-associated genes, but they regulated most genes in opposite directions. Further identified the involvement of oxidative stress and mediation analysis showed that the mediation effect of 8-hydroxydeoxyguanosine (8-OHdG) on 1-OH-Pyr-LMR association presented heterogeneity between low and high tin tertile groups (I2 = 37.84%).

CONCLUSION

1-OH-Pyr and tin were significantly associated with LMR. Modification effects indicated that the inverse association of 1-OH-Pyr with LMR was mitigated with an increase in tin. The mediation effect of 8-OHdG on the inverse association of 1-OH-Pyr with LMR may be partially dependent on tin.

Psychosocial factors, health behaviors and risk of cancer incidence: Testing interaction and effect modification in an individual participant data meta-analysis

Depression, anxiety and other psychosocial factors are hypothesized to be involved in cancer development. We examined whether psychosocial factors interact with or modify the effects of health behaviors, such as smoking and alcohol use, in relation to cancer incidence. Two-stage individual participant data meta-analyses were performed based on 22 cohorts of the PSYchosocial factors and CAncer (PSY-CA) study. We examined nine psychosocial factors (depression diagnosis, depression symptoms, anxiety diagnosis, anxiety symptoms, perceived social support, loss events, general distress, neuroticism, relationship status), seven health behaviors/behavior-related factors (smoking, alcohol use, physical activity, body mass index, sedentary behavior, sleep quality, sleep duration) and seven cancer outcomes (overall cancer, smoking-related, alcohol-related, breast, lung, prostate, colorectal). Effects of the psychosocial factor, health behavior and their product term on cancer incidence were estimated using Cox regression. We pooled cohort-specific estimates using multivariate random-effects meta-analyses. Additive and multiplicative interaction/effect modification was examined. This study involved 437,827 participants, 36,961 incident cancer diagnoses, and 4,749,481 person years of follow-up. Out of 744 combinations of psychosocial factors, health behaviors, and cancer outcomes, we found no evidence of interaction. Effect modification was found for some combinations, but there were no clear patterns for any particular factors or outcomes involved. In this first large study to systematically examine potential interaction and effect modification, we found no evidence for psychosocial factors to interact with or modify health behaviors in relation to cancer incidence. The behavioral risk profile for cancer incidence is similar in people with and without psychosocial stress.

The intersecting effects of race, wealth, and education on AIDS incidence, mortality, and case-fatality rate: a Brazilian cohort study of 28.3 million individuals

The relationships between race, education, wealth, their intersections and AIDS morbidity/mortality were analyzed in retrospective cohort of 28.3 million individuals followed for 9 years (2007-2015). Together with several sensitivity analyses, a wide range of interactions on additive and multiplicative scales were estimated. Race, education, and wealth were each strongly associated with all of the AIDS-related outcomes, and the magnitude of the associations increased as intersections were included. A significantly higher risk of illness (aRR: 3.07, 95%CI:2.67-3.53) and death (aRR: 4.96, 95%CI:3.99-6.16) from AIDS was observed at the intersection of Black race, lower educational attainment, and less wealth. A higher case-fatality rate (aRR: 1.62, 95%CI:1.18-2.21) was also seen for the same intersectional group. Historically oppressed groups lying at the intersections of race, education, and wealth, had a considerably higher risk of illness and death from AIDS. AIDS-related interventions will require the implementation of comprehensive intersectoral policies that follow an intersectionality perspective.

Dietary intake of vitamin C and gastric cancer: a pooled analysis within the Stomach cancer Pooling (StoP) Project

BACKGROUND

Previous studies suggest that dietary vitamin C is inversely associated with gastric cancer (GC), but most of them did not consider intake of fruit and vegetables. Thus, we aimed to evaluate this association within the Stomach cancer Pooling (StoP) Project, a consortium of epidemiological studies on GC.

METHODS

Fourteen case-control studies were included in the analysis (5362 cases, 11,497 controls). We estimated odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the association between dietary intake of vitamin C and GC, adjusted for relevant confounders and for intake of fruit and vegetables. The dose-response relationship was evaluated using mixed-effects logistic models with second-order fractional polynomials.

RESULTS

Individuals in the highest quartile of dietary vitamin C intake had reduced odds of GC compared with those in the lowest quartile (OR: 0.64; 95% CI: 0.58, 0.72). Additional adjustment for fruit and vegetables intake led to an OR of 0.85 (95% CI: 0.73, 0.98). A significant inverse association was observed for noncardia GC, as well as for both intestinal and diffuse types of the disease. The results of the dose-response analysis showed decreasing ORs of GC up to 150-200 mg/day of vitamin C (OR: 0.54; 95% CI: 0.41, 0.71), whereas ORs for higher intakes were close to 1.0.

CONCLUSIONS

The findings of our pooled study suggest that vitamin C is inversely associated with GC, with a potentially beneficial effect also for intakes above the currently recommended daily intake (90 mg for men and 75 mg for women).

Trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6-related dietary patterns in association with stroke risk

BACKGROUND AND AIMS

The aim of this study was to examine the associations of dietary patterns derived by reduced-rank regression (RRR) model reflecting variation in novel biomarkers (trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6) with stroke risk.

METHODS AND RESULTS

We performed analyses based on a community-based cohort study "the Prospective Follow-up Study on Cardiovascular Morbidity and Mortality in China (PFS-CMMC)". Factor loadings were calculated by RRR using 11 food groups collected via a validated food frequency questionnaire and the four response variables based on its nested case-control data (393 cases of stroke vs. 393 matched controls). Dietary pattern scores were derived by applying the factor loadings to the food groups in the entire cohort (n = 15,518). The associations of dietary pattern with the stroke risk were assessed using Cox proportional hazards models. The dietary pattern characterized with higher intakes of red meat and poultry but lower intakes of fresh vegetables, fresh fruits, and fish/seafoods were identified for further analyses. The hazard ratios (HR) for the highest vs. lowest quartile was 1.55 [95 % confidence interval (CI): 1.18-2.03, P trend = 0.001] for total stroke, 2.96 [95 % CI: 1.53-5.71, P trend <0.001] for non-ischemic stroke, after adjustment for sex, age, educational attainment, current smoking, current drinking, body mass index, total energy intake, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate.

CONCLUSION

Our findings highlight the importance of limited meat intake and increased intakes of fresh vegetables, fruits, and fish/seafoods in the prevention of stroke among Chinese adults.

Association between Diabetes and Exfoliation Syndrome

Topic

This systematic review and meta-analysis summarizes the existing evidence for the association of diabetes mellitus (DM) and exfoliation syndrome (XFS).

Clinical Relevance

Understanding and quantifying these associations may aid clinical guidelines or treatment strategies and shed light on disease pathogenesis. The role of DM in determining XFS risk may also be of interest from an individual or public health perspective.

Methods

The study protocol was preregistered on the International Prospective Register of Systematic Reviews with registration number CRD42023429771. We systematically searched PubMed and Embase from inception to June 15, 2023. Screening and full-text review were conducted by 2 independent reviewers. All observational studies reporting an age-adjusted odds ratio (OR) and 95% confidence interval (CI) for the association between DM and XFS among adults were included. Quantitative synthesis involved a random-effects meta-analysis using the DerSimonian-Laird method to generate a pooled OR. Risk of bias was evaluated using the Newcastle-Ottawa Scale.

Results

Fourteen studies (9 cross-sectional and 5 case-control) comprising 47 853 participants were included in the systematic review and meta-analysis. Random-effects meta-analysis indicated no overall association between DM and XFS (OR 0.94; 95% CI, 0.73–1.21; I 2  = 68.5%). However, subgroup analysis revealed a significant inverse association among individuals ≥ 65 years (OR 0.71; 95% CI, 0.54–0.93) versus individuals < 65 years (OR 1.22; 95% CI, 0.80–1.87; P effect modification  = 0.04). The relation between DM and XFS was also inverse in case-control studies (OR 0.75; 95% CI, 0.58–0.97) but was nonsignificant in cross-sectional studies (OR 1.17; 95% CI, 0.83–1.66; P effect modification  = 0.04). Overall risk of bias was low, with tests for publication bias showing P  ≥ 0.06.

Conclusion

This meta-analysis suggests no association between DM and XFS overall, with possible inverse associations of DM with XFS in older populations. However, given the substantial heterogeneity and borderline significance for publication bias, these findings should be interpreted with caution. Our results give insight into the unique etiology and clinical relevance of XFS while proposing the need for larger longitudinal and genetic biomarker studies.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The protective effect of CALD identity in the presence of low income on missing teeth of Australian adults over time

BACKGROUND

'Culturally And Linguistically Diverse (CALD)' populations have diverse languages, ethnic backgrounds, societal structures and religions. CALD populations have not experienced the same oral health benefits as non-CALD groups in Australia. However, the socio-demographic profile of Australian CALD populations is changing. This study examined how household income modifies the oral health of CALD and non-CALD adults in Australia.

METHODS

Data were from two National Surveys of Adult Oral Health (NSAOH) conducted in 2004-06 (NSAOH 2004-06) and 2017-18 (NSAOH 2017-18). The outcome was self-reported number of missing teeth. CALD status was identified based on English not the primary language spoken at home and country of birth not being Australia. Social disadvantage was defined by total annual household income. Effect-measure modification was used to verify differences on effect sizes per strata of CALD status and household income. The presence of modification was indicated by Relative Excess Risk due to Interactions (RERIs).

RESULTS

A total of 14,123 participants took part in NSAOH 2004-06. The proportion identifying as CALD was 11.7% and 56.7% were in the low-income group, and the mean number of missing teeth was 6.9. A total of 15,731 participants took part in NSAOH 2017-18. The proportion identifying as CALD was 18.5% and 38.0% were in the low-income group, and the mean number of missing teeth was 6.2. In multivariable modelling, the mean ratio (MR) for CALD participants with low household income in 2004-06 was 2% lower than the MR among non-CALD participants with high household income, with the RERI being - 0.23. Non-CALD participants from lower income households had a higher risk of having a higher number of missing teeth than low income CALD individuals (MR = 1.66, 95%CI 1.57-1.74 vs. MR = 1.43 95%CI 1.34-1.52, respectively). In 2017-18, the MR for CALD participants with low household income was 3% lower than the MR among non-CALD participants with high household income, with the RERI being - 0.11. Low income CALD participants had a lower risk of missing teeth compared to their non-CALD counterparts (MR = 1.43, 95% CI 1.34-1.52 vs. MR = 1.57, 95% CI 1.50-1.64).

CONCLUSIONS

The negative RERI values indicate that the effect-measure modification operates in a negative direction, that is, there is a protective element to being CALD among low income groups with respect to mean number of missing teeth.

Dietary intake of copper and gastric cancer: a pooled analysis within the Stomach cancer Pooling (StoP) Project

BACKGROUND

Evidence on the potential association between dietary copper intake and gastric cancer (GC) is lacking. Thus, we aimed to evaluate this association within the Stomach cancer Pooling (StoP) Project-an international consortium of epidemiological studies on GC.

METHODS

Data from five case-control studies within the StoP Project were included (2448 cases, 4350 controls). We estimated adjusted odds ratios (ORs) and 95% CIs for the association between dietary copper intake and GC using multivariable mixed-effects logistic regression models. We also modelled the dose-response relationship between copper intake and GC using a logistic mixed-effects model with fractional polynomial.

RESULTS

The OR for the highest quartile of copper intake compared with the lowest one was 0.78 (95% CI: 0.63-0.95; P for trend = 0.013). Results were similar for non-cardia-type (OR: 0.72; 95% CI: 0.57-0.91), intestinal-type (OR: 0.75; 95% CI: 0.56-0.99) and other histological-type GC (OR: 0.65; 95% CI: 0.44-0.96). The dose-response analysis showed a steep decrease in ORs for modest intakes (<1 mg/day), which were subsequently steady for ≤3 mg/day (OR: 0.09; 95% CI: 0.02-0.41) and slowly increased for higher intakes.

CONCLUSIONS

The findings of our large study suggest that copper intake might be inversely associated with GC, although their confirmation by prospective studies is required.

Additive interaction of family medical history of diabetes with hypertension on the diagnosis of diabetes among older adults in India: longitudinal ageing study in India

BACKGROUND

The present study aimed to estimate the additive interaction of family history of diabetes and hypertension on the diagnosis of diabetes among individuals aged 45 years and above in India. The coexistence of these two exposures may act synergistically on the risk of diabetes, leading to adverse health outcomes.

METHODS

The study utilized the data from the Longitudinal Ageing Study in India (LASI) Wave 1 (2017-2018). The total sample size for the current study was 58,612 individuals aged 45 years and above. Multivariable logistic regression models were employed to determine the individual and joint effect of a family history of diabetes with hypertension on diabetes. An additive model was applied to assess the interaction effect of the family medical history of diabetes with hypertension on the diagnosis of diabetes by calculating three different measures of additive interaction such as the relative excess risk ratio (RERI), attribution proportion due to interaction (AP), and synergy index (S).

RESULTS

The prevalence of diabetes was three times higher among individuals with family history of diabetes (27.8% vs. 9.2%) than those without family history. Individuals with family history of diabetes (AOR: 2.47, CI: 2.11 2.89) had 2.47 times higher odds of having diabetes than those without family history. The prevalence of diabetes was significantly higher among individuals with hypertension and family history of diabetes (46.6%, 95% CI: 39.7-53.6) than those without the coexistence of family history of diabetes and hypertension (9.9%, 95% CI: 9.5-10.4), individuals with hypertension and without a family history of diabetes (22.7%, 95% CI: 21.2-24.2), and individuals with family history of diabetes and without hypertension (16.5%, 95% CI: 14.5-18.7). Moreover, the adjusted odds ratio (AOR) of the joint effect between family medical history of diabetes and hypertension on diabetes was 9.28 (95% CI: 7.51-11.46). In the adjusted model, the RERI, AP, and S for diabetes were 3.5 (95% CI: 1.52-5.47), 37% (0.37; 95% CI: 0.22-0.51), and 1.69 (95% CI: 1.31-2.18) respectively, which indicates that there is a significant positive interaction between family history of diabetes and hypertension on the diagnosis of diabetes. The study findings on interaction effects further demonstrate consistent results for two models of hypertension (self-reported hypertension and hypertensive individuals receiving medication) even after adjustment with potential confounding factors on diabetes (self-reported diabetes and individuals with diabetes receiving medication).

CONCLUSIONS

The study findings strongly suggest that the interaction of family history of diabetes with hypertension has a positive and significant effect on the risk of diabetes even after adjustment with potential confounding factors. Furthermore, the findings indicate a synergistic effect, emphasizing the importance of considering both family medical history of diabetes and hypertension when assessing diabetes risk and designing preventive strategies or interventions.

Discovering Subgroups of Children With High Mortality in Urban Guinea-Bissau: Exploratory and Validation Cohort Study

BACKGROUND

The decline in global child mortality is an important public health achievement, yet child mortality remains disproportionally high in many low-income countries like Guinea-Bissau. The persisting high mortality rates necessitate targeted research to identify vulnerable subgroups of children and formulate effective interventions.

OBJECTIVE

This study aimed to discover subgroups of children at an elevated risk of mortality in the urban setting of Bissau, Guinea-Bissau, West Africa. By identifying these groups, we intend to provide a foundation for developing targeted health interventions and inform public health policy.

METHODS

We used data from the health and demographic surveillance site, Bandim Health Project, covering 2003 to 2019. We identified baseline variables recorded before children reached the age of 6 weeks. The focus was on determining factors consistently linked with increased mortality up to the age of 3 years. Our multifaceted methodological approach incorporated spatial analysis for visualizing geographical variations in mortality risk, causally adjusted regression analysis to single out specific risk factors, and machine learning techniques for identifying clusters of multifactorial risk factors. To ensure robustness and validity, we divided the data set temporally, assessing the persistence of identified subgroups over different periods. The reassessment of mortality risk used the targeted maximum likelihood estimation (TMLE) method to achieve more robust causal modeling.

RESULTS

We analyzed data from 21,005 children. The mortality risk (6 weeks to 3 years of age) was 5.2% (95% CI 4.8%-5.6%) for children born between 2003 and 2011, and 2.9% (95% CI 2.5%-3.3%) for children born between 2012 and 2016. Our findings revealed 3 distinct high-risk subgroups with notably higher mortality rates, children residing in a specific urban area (adjusted mortality risk difference of 3.4%, 95% CI 0.3%-6.5%), children born to mothers with no prenatal consultations (adjusted mortality risk difference of 5.8%, 95% CI 2.6%-8.9%), and children from polygamous families born during the dry season (adjusted mortality risk difference of 1.7%, 95% CI 0.4%-2.9%). These subgroups, though small, showed a consistent pattern of higher mortality risk over time. Common social and economic factors were linked to a larger share of the total child deaths.

CONCLUSIONS

The study's results underscore the need for targeted interventions to address the specific risks faced by these identified high-risk subgroups. These interventions should be designed to work to complement broader public health strategies, creating a comprehensive approach to reducing child mortality. We suggest future research that focuses on developing, testing, and comparing targeted intervention strategies unraveling the proposed hypotheses found in this study. The ultimate aim is to optimize health outcomes for all children in high-mortality settings, leveraging a strategic mix of targeted and general health interventions to address the varied needs of different child subgroups.

Do early-life allergic sensitization and respiratory infection interact to increase asthma risk?

OBJECTIVE

The 'two-hit' hypothesis theorizes that early life allergic sensitization and respiratory infection interact to increase asthma risk.

METHODS

We sought to determine in a high allergy risk birth cohort whether interactions between early life allergic sensitization and respiratory infection were associated with increased risk for asthma at ages 6-7 years and 18 years. Allergic sensitization was assessed at 6, 12, and 24 months by skin prick testing to 3 food and 3 aeroallergens. Respiratory infection was defined as reported "cough, rattle, or wheeze" and assessed 4-weekly for 15 months, at 18 months, and age 2 years. Regression analysis was undertaken with parent-reported asthma at age 6-7 years and doctor diagnosed asthma at 18 years as distinct outcomes. Interactions between allergic sensitization and respiratory infection were explored with adjustment made for potential confounders.

RESULTS

Odds of asthma were higher in sensitized compared to nonsensitized children at age 6-7 years (OR = 14.46; 95% CI 3.99-52.4), There was no evidence for interactions between allergic sensitization and early life respiratory infection, with a greater frequency of respiratory infection up to 2 years of age associated with increased odds for asthma at age 6-7 years in both sensitized (OR = 1.13; 95% CI 1.02-1.25, n = 199) and nonsensitized children (OR = 1.31; 1.11-1.53, n = 211) (p interaction = 0.089). At age 18 years, these associations were weaker.

CONCLUSIONS

Our findings do not support 'two-hit' interactions between early life allergic sensitization and respiratory infection on asthma risk. Both early life respiratory infections and allergic sensitization were risk factors and children with either should be monitored closely for development of asthma.

Clinical Predictors and Outcomes of Invasive Anal Cancer for People With Human Immunodeficiency Virus in an Inception Cohort

BACKGROUND

Due to the heterogeneity of risk for invasive anal cancer (IAC) among people with human immunodeficiency virus (PWH), we investigated predictors of IAC and described outcomes among those with a cancer diagnosis.

METHODS

Using a longitudinal inception cohort of anal cancer screening, we evaluated risk factors and outcome probabilities for incident IAC in Cox models. Screening included anal cytology and digital anorectal examination, and, if results of either were abnormal, high-resolution anoscopy.

RESULTS

Between 30 November 2006 and 3 March 2021, a total of 8139 PWH received care at the University of California, San Diego, with 4105 individuals undergoing screening and subsequently followed up over a median of 5.5 years. Anal cancer developed in 33 of them. IAC was more likely to develop in patients with anal high-grade squamous intraepithelial lesions (aHSILs) on initial or subsequent follow-up cytology (hazard ratio, 4.54) and a nadir CD4 cell count ≤200/µL (2.99). The joint effect of aHSILs and nadir CD4 cell count ≤200/µL amplified the hazard of IAC by 9-fold compared with the absence of both. PWH with time-updated cytology aHSIL and CD4 cell counts ≤200/µL had 5- and 10-year probabilities of IAC of 3.40% and 4.27%, respectively. Twelve individuals with cancer died, 7 (21% of the total 33) due to cancer progression, and they had clinical stage IIIA or higher cancer at initial diagnosis.

CONCLUSIONS

PWH with both aHSIL and a nadir CD4 cell count ≤200/µL have the highest risk of IAC. PWH who died due to IAC progression had clinical stage IIIA cancer or higher at diagnosis, highlighting the importance of early diagnosis through high-resolution anoscopic screening.

Many roads to a gene-environment interaction

Despite the importance of gene-environment interactions (GxEs) in improving and operationalizing genetic discovery, interpretation of any GxEs that are discovered can be surprisingly difficult. There are many potential biological and statistical explanations for a statistically significant finding and, likewise, it is not always clear what can be claimed based on a null result. A better understanding of the possible underlying mechanisms leading to a detected GxE can help investigators decide which are and which are not relevant to their hypothesis. Here, we provide a detailed explanation of five "phenomena," or data-generating mechanisms, that can lead to nonzero interaction estimates, as well as a discussion of specific instances in which they might be relevant. We hope that, given this framework, investigators can design more targeted experiments and provide cleaner interpretations of the associated results.

Exposure to Concurrent Heatwaves and Ozone Pollution and Associations with Mortality Risk: A Nationwide Study in China

BACKGROUND

Concurrent extreme events are projected to occur more frequently under a changing climate. Understanding the mortality risk and burden of the concurrent heatwaves and ozone (O 3 ) pollution may support the formulation of adaptation strategies and early warning systems for concurrent events in the context of climate change.

OBJECTIVES

We aimed to estimate the mortality risk and excess deaths of concurrent heatwaves and O 3 pollution across 250 counties in China.

METHODS

We collected daily mortality, meteorological, and air pollution data for the summer (1 June to 30 September) during 2013-2018. We defined heatwaves and high O 3 pollution days, then we divided the identified days into three categories: a) days with only heatwaves (heatwave-only event), b) days with only high O 3 pollution (high O 3 pollution-only event), and c) days with concurrent heatwaves and high O 3 pollution (concurrent event). A generalized linear model with a quasi-Poisson regression was used to estimate the risk of mortality associated with extreme events for each county. Then we conducted a random-effects meta-analysis to pool the county-specific estimates to derive the overall effect estimates. We used mixed-effects meta-regression to identify the drivers of the heterogeneity. Finally, we estimated the excess death attributable to extreme events (heatwave-only, high O 3 pollution-only, and concurrent events) from 2013 to 2020.

RESULTS

A higher all-cause mortality risk was associated with exposure to the concurrent heatwaves and high O 3 pollution than exposure to a heatwave-only or a high O 3 pollution-only event. The effects of a concurrent event on circulatory and respiratory mortality were higher than all-cause and nonaccidental mortality. Sex and age significantly impacted the association of concurrent events and heatwave-only events with all-cause mortality. We estimated that annual average excess deaths attributed to the concurrent events were 6,249 in China from 2017 to 2020, 5.7 times higher than the annual average excess deaths attributed to the concurrent events from 2013 to 2016. The annual average proportion of excess deaths attributed to the concurrent events in the total excess deaths caused by three types of events (heatwave-only events, high O 3 pollution-only events, and concurrent events) increased significantly in 2017-2020 (31.50%; 95% CI: 26.73%, 35.53%) compared with 2013-2016 (9.65%; 95% CI: 5.67%, 10.81%). Relative excess risk due to interaction revealed positive additive interaction considering the concurrent effect of heatwaves and high O 3 pollution.

DISCUSSION

Our findings may provide scientific basis for establishing a concurrent event early warning system to reduce the adverse health impact of the concurrent heatwaves and high O 3 pollution. https://doi.org/10.1289/EHP13790.

Heterogeneous Association of Tooth Loss with Functional Limitations

Tooth loss is prevalent in older adults and associated with functional capacity decline. Studies on the susceptibility of some individuals to the effects of tooth loss are lacking. This study aimed to investigate the heterogeneity of the association between tooth loss and higher-level functional capacity in older Japanese individuals employing a machine learning approach. This is a prospective cohort study using the data of adults aged ≥65 y in Japan (N = 16,553). Higher-level functional capacity, comprising instrumental independence, intellectual activity, and social role, was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC). The scale ranged from 0 (lowest function) to 13 (highest function). Doubly robust targeted maximum likelihood estimation was used to estimate the population-average association between tooth loss (having <20 natural teeth) and TMIG-IC total score after 6 y. The heterogeneity of the association was evaluated by estimating conditional average treatment effects (CATEs) using the causal forest algorithm. The result showed that tooth loss was statistically significantly associated with lower TMIG-IC total scores (population-average effect: -0.14; 95% confidence interval, -0.18 to -0.09). The causal forest analysis revealed the heterogeneous associations between tooth loss and lower TMIG-IC total score after 6 y (median of estimated CATEs = -0.13; interquartile range = 0.12). The high-impact subgroup (i.e., individuals with estimated CATEs of the bottom 10%) were significantly more likely to be older and male, had a lower socioeconomic status, did not have a partner, and had poor health conditions compared with the low-impact subgroup (i.e., individuals with estimated CATEs of the top 10%). This study found that heterogeneity exists in the association between tooth loss and lower scores on functional capacity. Implementing tooth loss prevention policy and clinical measures, especially among vulnerable subpopulations significantly affected by tooth loss, may reduce its burden more effectively.