The Interaction Continuum

Effects of depression and cognitive impairment on increased risks of incident dementia: a prospective study from three elderly cohorts

Depression is usually accompanied with cognitive impairment and increases risk of incident dementia. However, evidence has been limited on the effect size of depression with cognitive impairment and their synergistic effect on future dementia. To explore this, we examined three large cross-country population-based prospective cohorts. Depressive symptoms were assessed by epidemiologic scale, while cognitive impairment was defined by subjective cognitive tests. Dementia was ascertained by self-reported physician-diagnosed conditions. Cox proportional hazard models were employed to determine the hazard ratio (HR) and 95% confidence interval (95% CI), with adjustments of potential confounding variables. Addictive and multiplicative interactions were calculated to evaluate the synergistic effect. A total of 64,706 participants were included at baseline (mean age: 63.9, female: 55.2%), where 4197 (6.5%) individuals had depressive symptoms only, 28,175 (43.5%) individuals had cognitive impairment only, 11,564 (17.9%) individuals had both, and 20,770 (32.1%) individuals had neither. Compared with the neither group, all the other three groups had higher risks of subsequent dementia (depression only: HR 1.65, 95% CI 1.26-2.17; cognitive impairment only: HR 2.71, 95% CI 2.33-3.14; depression with cognitive impairment: HR 3.51, 95% CI 2.95-4.17). There was insignificant additive (RERI, 0.15, 95% CI -0.45-0.75; AP, 0.042, 95% CI -0.13-0.21; SI, 1.06, 95% CI 0.83-1.37) and multiplicative (0.78, 95% CI 0.58-1.06) interaction between depression and cognitive impairment on subsequent dementia. We found depression with cognitive impairment has higher risks of dementia than either condition alone and no significant synergistic effect exists between these two factors.

Clinical Predictors and Outcomes of Invasive Anal Cancer for People With HIV 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.

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.

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.

First-Attempt Success Between Anatomically and Physiologically Difficult Airways in the National Emergency Airway Registry

BACKGROUND

In the emergency department (ED), certain anatomical and physiological airway characteristics may predispose patients to tracheal intubation complications and poor outcomes. We hypothesized that both anatomically difficult airways (ADAs) and physiologically difficult airways (PDAs) would have lower first-attempt success than airways with neither in a cohort of ED intubations.

METHODS

We performed a retrospective, observational study using the National Emergency Airway Registry (NEAR) to examine the association between anticipated difficult airways (ADA, PDA, and combined ADA and PDA) vs those without difficult airway findings (neither ADA nor PDA) with first-attempt success. We included adult (age ≥14 years) ED intubations performed with sedation and paralysis from January 1, 2016 to December 31, 2018 using either direct or video laryngoscopy. We excluded patients in cardiac arrest. The primary outcome was first-attempt success, while secondary outcomes included first-attempt success without adverse events, peri-intubation cardiac arrest, and the total number of airway attempts. Mixed-effects models were used to obtain adjusted estimates and confidence intervals (CIs) for each outcome. Fixed effects included the presence of a difficult airway type (independent variable) and covariates including laryngoscopy device type, intubator postgraduate year, trauma indication, and patient age as well as the site as a random effect. Multiplicative interaction between ADAs and PDAs was assessed using the likelihood ratio (LR) test.

RESULTS

Of the 19,071 subjects intubated during the study period, 13,938 were included in the study. Compared to those without difficult airway findings (neither ADA nor PDA), the adjusted odds ratios (aORs) for first-attempt success were 0.53 (95% CI, 0.40-0.68) for ADAs alone, 0.96 (0.68-1.36) for PDAs alone, and 0.44 (0.34-0.56) for both. The aORs for first-attempt success without adverse events were 0.72 (95% CI, 0.59-0.89) for ADAs alone, 0.79 (0.62-1.01) for PDAs alone, and 0.44 (0.37-0.54) for both. There was no evidence that the interaction between ADAs and PDAs for first-attempt success with or without adverse events was different from additive (ie, not synergistic/multiplicative or antagonistic).

CONCLUSIONS

Compared to no difficult airway characteristics, ADAs were inversely associated with first-attempt success, while PDAs were not. Both ADAs and PDAs, as well as their interaction, were inversely associated with first-attempt success without adverse events.

Exploring a Potential Interaction Between the Effect of Specific Maternal Smoking Patterns and Comorbid Antenatal Depression in Causing Postpartum Depression

Purpose

To explore a potential interaction between the effect of specific maternal smoking patterns and the presence of antenatal depression, as independent exposures, in causing postpartum depression (PPD).

Methods

This case-control study of participants with singleton term births (N = 51220) was based on data from the 2017-2018 Pregnancy Risk Assessment Monitoring System. Multivariable log-binomial regression models examined the main effects of smoking patterns and self-reported symptoms of antenatal depression on the risk of PPD on the adjusted risk ratio (aRR) scale and tested a two-way interaction adjusting for covariates selected in a directed acyclic graph (DAG). The interaction effects were measured on the additive scale using relative excess risk due to interaction (RERI), the attributable proportion of interaction (AP), and the synergy index (SI). Causal effects were defined in a counterfactual framework. The E-value quantified the potential impact of unobserved/unknown covariates, conditional on observed covariates.

Results

Among 6841 women in the sample who self-reported PPD, 35.7% also reported symptoms of antenatal depression. Out of 3921 (7.7%) women who reported smoking during pregnancy, 32.6% smoked at high intensity (≥10 cigarettes/day) in all three trimesters and 36.6% had symptoms of antenatal depression. The main effect of PPD was the strongest for women who smoked at high intensity throughout pregnancy (aRR 1.65; 95% CI: 1.63, 1.68). A synergistic interaction was detected, and the effect of all maternal smoking patterns was augmented, particularly in late pregnancy for Increasers and Reducers.

Conclusion

Strong associations and interaction effects between maternal smoking patterns and co-occurring antenatal depression support smoking prevention and cessation interventions during pregnancy to lower the likelihood of PPD.

Statistical inference on qualitative differences in the magnitude of an effect

Qualitative interactions occur when a treatment effect or measure of association varies in sign by sub-population. Of particular interest in many biomedical settings are absence/presence qualitative interactions, which occur when an effect is present in one sub-population but absent in another. Absence/presence interactions arise in emerging applications in precision medicine, where the objective is to identify a set of predictive biomarkers that have prognostic value for clinical outcomes in some sub-population but not others. They also arise naturally in gene regulatory network inference, where the goal is to identify differences in networks corresponding to diseased and healthy individuals, or to different subtypes of disease; such differences lead to identification of network-based biomarkers for diseases. In this paper, we argue that while the absence/presence hypothesis is important, developing a statistical test for this hypothesis is an intractable problem. To overcome this challenge, we approximate the problem in a novel inference framework. In particular, we propose to make inferences about absence/presence interactions by quantifying the relative difference in effect size, reasoning that when the relative difference is large, an absence/presence interaction occurs. The proposed methodology is illustrated through a simulation study as well as an analysis of breast cancer data from the Cancer Genome Atlas.

Who is more vulnerable to effects of long-term exposure to air pollution on COVID-19 hospitalisation?

OBJECTIVE

Factors that shape individuals' vulnerability to the effects of air pollution on COVID-19 severity remain poorly understood. We evaluated whether the association between long-term exposure to ambient NO2, PM2.5, and PM10 and COVID-19 hospitalisation differs by age, sex, individual income, area-level socioeconomic status, arterial hypertension, diabetes mellitus, and chronic obstructive pulmonary disease.

METHODS

We analysed a population-based cohort of 4,639,184 adults in Catalonia, Spain, during 2020. We fitted Cox proportional hazard models adjusted for several potential confounding factors and evaluated the interaction effect between vulnerability indicators and the 2019 annual average of NO2, PM2.5, and PM10. We evaluated interaction on both additive and multiplicative scales.

RESULTS

Overall, the association was additive between air pollution and the vulnerable groups. Air pollution and vulnerability indicators had a synergistic (greater than additive) effect for males and individuals with low income or living in the most deprived neighbourhoods. The Relative Excess Risk due to Interaction (RERI) was 0.21, 95 % CI, 0.15 to 0.27 for NO2 and 0.16, 95 % CI, 0.11 to 0.22 for PM2.5 for males; 0.13, 95 % CI, 0.09 to 0.18 for NO2 and 0.10, 95 % CI, 0.05 to 0.14 for PM2.5 for lower individual income and 0.17, 95 % CI, 0.12 to 0.22 for NO2 and 0.09, 95 % CI, 0.05 to 0.14 for PM2.5 for lower area-level socioeconomic status. Results for PM10 were similar to PM2.5. Results on multiplicative scale were inconsistent.

CONCLUSIONS

Long-term exposure to air pollution had a larger synergistic effect on COVID-19 hospitalisation for males and those with lower individual- and area-level socioeconomic status.

Interaction between benzodiazepines and prescription opioids on incidence of hard braking events in older drivers

BACKGROUND

Polypharmacy use among older adults is of increasing concern for driving safety. This study assesses the individual and joint effects of benzodiazepines and prescription opioids on the incidence of hard braking events in older drivers.

METHODS

Data for this study came from the Longitudinal Research on Aging Drivers project-a multisite, prospective cohort study of 2990 drivers aged 65-79 years at enrollment (2015-2017). Adjusted incidence rate ratios (aIRRs) and 95% confidence intervals (CIs) of hard braking events (defined as maneuvers with deceleration rates ≥0.4 g and commonly known as near-crashes) were estimated through multivariable negative binominal modeling.

RESULTS

Of the 2929 drivers studied, 167 (5.7%) were taking benzodiazepines,  163 (5.6%) prescription opioids, and 23 (0.8%) both drugs at baseline. The incidence rates of hard braking events per 1000 miles driven were 1.14 (95% CI 1.10-1.18) for drivers using neither benzodiazepines nor prescription opioids, 1.25 (95% CI 1.07-1.43) for those using benzodiazepines only, 1.55 (95% CI 1.35-1.76) for those using prescription opioids only, and 1.63 (95% CI 1.11-2.16) for those using both medications. Multivariable modeling revealed that the use of prescription opioids was associated with a 19% increased risk of hard braking events (aIRR 1.19, 95% CI 1.03-1.36). There existed a positive interaction between the two drugs on the additive scale but not on the multiplicative scale.

CONCLUSION

Concurrent use of benzodiazepines and prescription opioids by older drivers appears to affect driving safety through increased incidence of hard braking events.

Have We Been Underestimating Modifiable Dementia Risk? An Alternative Approach for Calculating the Combined Population Attributable Fraction for Modifiable Dementia Risk Factors

Estimating the fraction of dementia cases in a population attributable to a risk factor or combination of risk factors (the population attributable fraction (PAF)) informs the design and choice of dementia risk-reduction activities. It is directly relevant to dementia prevention policy and practice. Current methods employed widely in the dementia literature to combine PAFs for multiple dementia risk factors assume a multiplicative relationship between factors and rely on subjective criteria to develop weightings for risk factors. In this paper we present an alternative approach to calculating the PAF based on sums of individual risk. It incorporates individual risk factor interrelationships and enables a range of assumptions about the way in which multiple risk factors will combine to affect dementia risk. Applying this method to global data demonstrates that the previous estimate of 40% is potentially too conservative an estimate of modifiable dementia risk and would necessitate subadditive interaction between risk factors. We calculate a plausible conservative estimate of 55.7% (95% confidence interval: 55.2, 56.1) based on additive risk factor interaction.

Interaction between plasma phospholipid odd-chain fatty acids and GAD65 autoantibodies on the incidence of adult-onset diabetes: the EPIC-InterAct case-cohort study

AIMS/HYPOTHESIS

Islet autoimmunity may progress to adult-onset diabetes. We investigated whether circulating odd-chain fatty acids (OCFA) 15:0 and 17:0, which are inversely associated with type 2 diabetes, interact with autoantibodies against GAD65 (GAD65Ab) on the incidence of adult-onset diabetes.

METHODS

We used the European EPIC-InterAct case-cohort study including 11,124 incident adult-onset diabetes cases and a subcohort of 14,866 randomly selected individuals. Adjusted Prentice-weighted Cox regression estimated HRs and 95% CIs of diabetes in relation to 1 SD lower plasma phospholipid 15:0 and/or 17:0 concentrations or their main contributor, dairy intake, among GAD65Ab-negative and -positive individuals. Interactions between tertiles of OCFA and GAD65Ab status were estimated by proportion attributable to interaction (AP).

RESULTS

Low concentrations of OCFA, particularly 17:0, were associated with a higher incidence of adult-onset diabetes in both GAD65Ab-negative (HR 1.55 [95% CI 1.48, 1.64]) and GAD65Ab-positive (HR 1.69 [95% CI 1.34, 2.13]) individuals. The combination of low 17:0 and high GAD65Ab positivity vs high 17:0 and GAD65Ab negativity conferred an HR of 7.51 (95% CI 4.83, 11.69), with evidence of additive interaction (AP 0.25 [95% CI 0.05, 0.45]). Low dairy intake was not associated with diabetes incidence in either GAD65Ab-negative (HR 0.98 [95% CI 0.94, 1.02]) or GAD65Ab-positive individuals (HR 0.97 [95% CI 0.79, 1.18]).

CONCLUSIONS/INTERPRETATION

Low plasma phospholipid 17:0 concentrations may promote the progression from GAD65Ab positivity to adult-onset diabetes.

Understanding 'it depends' in ecology: a guide to hypothesising, visualising and interpreting statistical interactions

Ecologists routinely use statistical models to detect and explain interactions among ecological drivers, with a goal to evaluate whether an effect of interest changes in sign or magnitude in different contexts. Two fundamental properties of interactions are often overlooked during the process of hypothesising, visualising and interpreting interactions between drivers: the measurement scale - whether a response is analysed on an additive or multiplicative scale, such as a ratio or logarithmic scale; and the symmetry - whether dependencies are considered in both directions. Overlooking these properties can lead to one or more of three inferential errors: misinterpretation of (i) the detection and magnitude (Type-D error), and (ii) the sign of effect modification (Type-S error); and (iii) misidentification of the underlying processes (Type-A error). We illustrate each of these errors with a broad range of ecological questions applied to empirical and simulated data sets. We demonstrate how meta-analysis, a widely used approach that seeks explicitly to characterise context dependence, is especially prone to all three errors. Based on these insights, we propose guidelines to improve hypothesis generation, testing, visualisation and interpretation of interactions in ecology.

Social media, traditional media, and other body image influences and disordered eating and cosmetic procedures in Malaysia, Singapore, Thailand, and Hong Kong

In this study, we investigated the association between perceived sociocultural influences and the 3-month prevalence of disordered weight-control behaviors and lifetime prevalence of cosmetic procedures in four Asian countries, and if these associations were modified by gender. We conducted a cross-sectional online survey in September 2020 among adults ages 18-91 years (N = 5294) in Malaysia, Singapore, Thailand and Hong Kong. The 3-month prevalence of disordered weight control behaviors ranged from 25.2 % (Singapore) to 42.3 % (Malaysia), while the lifetime prevalence of cosmetic procedures ranged from 8.7 % (Singapore) to 21.3 % (Thailand). Participants who perceived their body image to be influenced by sociocultural factors were more likely to engage in disordered weight control behaviors (RRs ranged from 2.05 to 2.12) and have cosmetic procedures (RRs ranged from 2.91 to 3.89) compared to participants who perceived no sociocultural influence. Men who were influenced by traditional or social media were more likely to engage in disordered weight control behaviors and have cosmetic procedures than similarly influenced women. The high 3-month prevalence of disordered weight control behaviors and lifetime prevalence of cosmetic procedures in Asia is concerning. More research is needed to develop effective preventive interventions in Asia for men and women to promote a healthy body image.

Joint effect of highly-sensitive cardiac troponin T and ankle-brachial index on incident cardiovascular events: The MESA and CHS

Background

Elevated highly-sensitive cardiac troponin-T (hs-cTnT≥14 ng/L) and low ankle-brachial index (ABI<0.9) are risk factors for atherosclerotic cardiovascular diseases (ASCVD) but their joint effect on the risk of ASCVD events is unknown.

Methods

We used data from the two population-based cohort studies, the Multi-Ethnic study of Atherosclerosis (MESA) and Cardiovascular Heart Study (CHS) among 10,897 participants free of CVD events at baseline (mean age 66.3 years, 44.7% males). Incident ASCVD was defined as CHD (fatal/non-fatal MI or revascularization), transient ischemic attack, or stroke,. Hazard ratio (HR) and 95% CI was calculated from a Cox regression model. Interaction on the additive scale was assessed using relative excess risk due to interaction (RERI) and interaction on the multiplicative scale was assessed by Likelihood ratio (LR) test.

Results

At baseline (2000-2002 for MESA and 1989-1990 for CHS), 10.2% of participants had elevated hs-cTnT and 7.5% had low ABI. During a median follow-up of 13.6 years (interquartile range, 7.5-14.7 years), there were 2590 incident ASCVD and 1542 incident CHD events. The hazard of CHD and ASCVD was higher in participants with both elevated hs-cTnT and low ABI [HR(95% CI): CHD: 2.04 (1.45, 2.88), ASCVD: 2.05 (1.58, 2.66)] than those with only elevated hs-cTnT [CHD: 1.65 (1.37, 1.99), ASCVD: 1.67 (1.44, 1.99)] or only low ABI [CHD: 1.87 (1.52, 2.31), ASCVD: 1.67 (1.42, 1.97)]. Antagonistic multiplicative interaction was observed for CHD (LR test p-value=0.042) but not for ASCVD (LR test p-value =0.08). No significant additive interaction was detected for CHD and ASCVD (RERI p-value ≥0.23).

Conclusion

The observed joint effect of elevated cTnT and low ABI on ASCVD risk was smaller (i.e., antagonistic interaction) than that expected by the combined independent effects of each risk factor.

An assessment of enhanced biosecurity interventions and their impact on porcine reproductive and respiratory syndrome virus outbreaks within a managed group of farrow-to-wean farms, 2020-2021

Introduction

Porcine reproductive and respiratory syndrome virus (PRRSV) has been a challenge for the U.S. swine industry for over 30 years, costing producers more than $600 million annually through reproductive disease in sows and respiratory disease in growing pigs. In this study, the impact of enhanced biosecurity practices of site location, air filtration, and feed mitigation was assessed on farrow-to-wean sites managed by a large swine production management company in the Midwest United States. Those three factors varied in the system that otherwise had implemented a stringent biosecurity protocol on farrow-to-wean sites. The routine biosecurity followed commonplace activities for farrow-to-wean sites that included but were not limited to visitor registration, transport disinfection, shower-in/shower-out procedures, and decontamination and disinfection of delivered items and were audited.

Methods

Logistic regression was used to evaluate PRRSV infection by site based on the state where the site is located and air filtration use while controlling for other variables such as vaccine status, herd size, and pen vs. stall. A descriptive analysis was used to evaluate the impact of feed mitigation stratified by air filtration use.

Results

Sites that used feed mitigates as additives in the diets, air filtration of barns, and that were in less swine-dense areas appeared to experience fewer outbreaks associated with PRRSV infection. Specifically, 23.1% of farms that utilized a feed mitigation program experienced PRRSV outbreaks, in contrast to 100% of those that did not. Sites that did not use air filtration had 20 times greater odds of having a PRRSV outbreak. The strongest protective effect was found when both air filtration and feed mitigation were used. Locations outside of Minnesota and Iowa had 98.5-99% lesser odds of infection as well.

Discussion

Enhanced biosecurity practices may yield significant protective effects and should be considered for producers in swine-dense areas or when the site contains valuable genetics or many pigs.

Survival benefits of oral anticoagulation therapy in acute kidney injury patients with atrial fibrillation: a retrospective study from the MIMIC-IV database

OBJECTIVE

To find out the effect of different oral anticoagulation therapies (OAC) on mortality rate in patients with acute kidney injury (AKI) and atrial fibrillation (AF).DesignA retrospective study.

SETTING

This study was conducted in the Medical Information Mart for Intensive Care IV database.

PARTICIPANTS

A total of 19 672 patients diagnosed with AKI.

MAIN OUTCOME MEASURES

Patients were categorised into three groups: (1) AF; (2) AKI and AF, OAC-; (3) AKI and AF, OAC+. The primary endpoint was 30-day mortality. Secondary endpoints were the length of stay (LOS) in the intensive care unit (ICU) and hospital. Propensity score matching (PSM) and Cox proportional hazards model adjusted confounding factors. Linear regression was applied to assess the associations between OAC treatment and LOS.

RESULTS

After PSM, 2042 pairs of AKI and AF patients were matched between the patients who received OAC and those without anticoagulant treatment. Cox regression analysis showed that, OAC significantly reduce 30-day mortality compared with non-OAC (HR 0.30; 95% CI 0.25 to 0.35; p<0.001). Linear regression analysis revealed that OAC prolong LOS in hospital (11.3 days vs 10.0 days; p=0.013) and ICU (4.9 days vs 4.4 days; p<0.001). OAC did not improve survival in patients with haemorrhage (HR 0.67; 95% CI 0.34 to 1.29; p=0.23). Novel OAC did not reduce mortality in acute-on-chronic renal injury (HR 2.03; 95% CI 1.09 to 3.78; p=0.025) patients compared with warfarin.

CONCLUSION

OAC administration was associated with improved short-term survival in AKI patients concomitant with AF.

Interactions between ultrasonographic cervical length and placenta accreta spectrum on severe postpartum hemorrhage in women with placenta previa

OBJECTIVE

To explore the interactions between cervical length (CL) and placenta accreta spectrum (PAS) on severe postpartum hemorrhage (SPPH) in patients with placenta previa.

METHODS

A retrospective case-control study was conducted at four medical centers in China, and 588 patients with placenta previa were included. The logistic regression analysis and restricted cubic splines (RCS) were used to evaluate the association between CL and SPPH. Furthermore, the joint effect of CL and PAS on SPPH was assessed, and the additive and multiplicative interactions were calculated.

RESULTS

After adjusting for potential confounders, the negative linear dose-response relationship was confirmed by RCS, and the change of odds ratio (OR) was more significant when CL was 2.5 cm or less. The risk of SPPH was significantly higher when CL of 2.5 cm or less co-existed with placenta increta/percreta than when CL of 2.5 cm less, or placenta increta/percreta existed alone (adjusted OR [aOR]_{CL ≤2.5cm&placenta accreta/non-PAS} 3.40, 95% confidence interval [CI] 1.37-8.45; aOR_{placenta increta/percreta&CL >2.5cm} 4.75, 95% CI 3.03-7.47; aOR_{CL ≤2.5cm&placenta increta/percreta} 14.51, 95% CI 6.08-34.64), and there might be additive interaction between CL and placenta increta/percreta on SPPH (attributable proportion due to interaction 50.7%, 95% CI 6.1%-95.3%).

CONCLUSION

If CL was routinely performed during PAS evaluation, the increased OR of short CL and PAS could allow better patient preparation through counseling.

Is the Effect Larger in Group A or B? It Depends: Understanding Results From Nonlinear Probability Models

Demographers and other social scientists often study effect heterogeneity (defined here as differences in outcome-predictor associations across groups defined by the values of a third variable) to understand how inequalities evolve between groups or how groups differentially benefit from treatments. Yet answering the question "Is the effect larger in group A or group B?" is surprisingly difficult. In fact, the answer sometimes reverses across scales. For example, researchers might conclude that the effect of education on mortality is larger among women than among men if they quantify education's effect on an odds-ratio scale, but their conclusion might flip (to indicate a larger effect among men) if they instead quantify education's effect on a percentage-point scale. We illuminate this flipped-signs phenomenon in the context of nonlinear probability models, which were used in about one third of articles published in Demography in 2018-2019. Although methodologists are aware that flipped signs can occur, applied researchers have not integrated this insight into their work. We provide formal inequalities that researchers can use to easily determine if flipped signs are a problem in their own applications. We also share practical tips to help researchers handle flipped signs and, thus, generate clear and substantively correct descriptions of effect heterogeneity. Our findings advance researchers' ability to accurately characterize population variation.

Second primary malignancies in cervical cancer and endometrial cancer survivors: a population-based analysis

Background: We evaluated the relative attribution and interactions of treatment and patient-related risk factors for second primary malignancies (SPMs) in cervical and endometrial cancer survivors.

Methods: Stage I–III cervical and endometrial cancer survivors’ data from the Surveillance, Epidemiology, and End Results (SEER) registry between January 1988 and December 2015 were analyzed. The standardized incidence ratio (SIR), excess absolute risk (EAR), and corresponding 95% confidence interval (95% CI) values were calculated. Analyses were classified based on proxies of human papillomavirus (HPV), smoking, hormone, and radiotherapy (RT) status. Additive and multiplicative interactions were assessed.

Results: Cervical cancer survivors had a higher risk for developing potentially HPV and smoking-related SPMs, especially in the RT group (SIR_HPV = 3.7, 95% CI: 2.9–4.6; SIR_smoking = 3.2, 95% CI: 2.8–3.6). Second vaginal cancer patients had the highest SIR (23.8, 95% CI: 14.9–36.0). There were strong synergistic interactions between RT and the proxy of smoking (P_interaction < 0.001), accounting for 36% of potentially smoking-related SPMs in cervical cancer survivors.

Conclusions: RT, HPV, and smoking promote SPMs in cervical cancer to different extents. The SPM burden in cervical cancer survivors could be mostly attributed to smoking and RT and their interactions.

Periodontal disease and incident prediabetes and diabetes: The Hispanic Community Health Study/Study of Latinos

AIM

To examine whether baseline periodontal disease is independently associated with incident prediabetes and incident diabetes in Hispanics/Latinos in the United States.

MATERIALS AND METHODS

This study examined 7827 individuals, 18-74 years of age without diabetes, from the Hispanic Community Health Study/Study of Latinos. Participants received a full-mouth periodontal examination at baseline (2008-2011), and the disease was classified using the Centers for Disease Control and Prevention/American Academy of Periodontology case definitions. At Visit 2 (2014-2017), incident prediabetes and diabetes were assessed using multiple standard procedures including blood tests. Multivariable survey Poisson regressions estimated the rate ratio (RR) and 95% confidence intervals (CIs) of incident prediabetes and incident diabetes associated with periodontal disease severity.

RESULTS

Among the individuals without prediabetes or diabetes at baseline, 38.8% (n = 1553) had developed prediabetes and 2.2% (n = 87) had developed diabetes after 6 years. Nineteen percent (n = 727) of individuals with prediabetes at baseline developed diabetes after 6 years. Adjusting for all potential confounders, no significant association was found between periodontal disease severity and either incident prediabetes (RR: 0.93; 95% CI: 0.82-1.06) or incident diabetes (RR: 0.99; 95% CI: 0.80-1.22).

CONCLUSIONS

Our findings suggest that among a diverse cohort of Hispanic/Latino individuals living in the United States, there was no association between periodontal disease severity and the development of either prediabetes or diabetes during a 6-year follow-up period.

Adult-onset immunodeficiency due to anti-interferon-gamma autoantibody-associated Sweet syndrome: A distinctive entity

Sweet syndrome (SS) has been increasingly reported in patients with adult-onset immunodeficiency (AOID) due to anti-interferon-γ autoantibody who also have concomitant opportunistic infections, especially disseminated non-tuberculous mycobacterial infection (dNTMI). A retrospective study retrieving data from 2011 through 2020 was conducted. We compared clinical characteristics of SS with and without AOID and generated the prediction model and examined the interaction between AOID and dNTMI in the occurrence of SS. Lymphadenopathy, pustular lesions, and leukocytosis are the significant predictors for AOID-associated SS. Adjusted risk differences were 0.58 (95% confidence interval [CI], 0.33-0.83), 0.21 (95% CI, 0.02-0.39), and 0.24 (95% CI, 0.01-0.47), respectively. Based on the analysis of aggregated cross-sectional data, both the overall and the direct effect of AOID increased the prevalence of SS. The indirect effect of AOID on the occurrence of SS might also be mediated through dNTMI or other common opportunistic infections. In addition, there was a trend of positive additive interaction between AOID and dNTMI. Although the test of additive interaction did not reveal statistically significant results, a deviation from additivity of isolated effects might suggest potential causal interaction between AOID and dNTMI. The distinctive clinical syndrome comprising lymphadenopathy, pustular lesions, and leukocytosis in patients with SS should raise the awareness of clinicians to the potential of underlying AOID.

Associations Between Purpose in Life and Mortality by SES

INTRODUCTION

Having a higher purpose in life has been linked to favorable health outcomes. However, little research has examined whether the purpose-health association persists across different levels of SES. This study assesses whether the association between higher purpose in life and lower mortality is similar across the levels of SES.

METHODS

A national sample of 13,159 U.S. adults aged >50 years from the Health and Retirement Study was analyzed. The baseline year was 2006‒2008. Purpose in life was assessed at baseline using Purpose in Life Subscale of the Ryff Psychological Well-being Scales. The risk of death during an 8-year follow-up was assessed. SES was measured using education, income, and wealth. Using multivariable Poisson regression, effect modification by SES was tested on both the additive and multiplicative scales. Analyses were done in 2020.

RESULTS

In analyses stratified by SES, people with the highest level of purpose consistently tended to have lower mortality risk across the levels of SES than those with the lowest level of purpose. However, people with middle-range purpose levels had lower mortality risk only if they also had mid-to-high education, income, and wealth. When formally testing the effect modification by SES, there was modest evidence that the associations between higher purpose and lower mortality were stronger among individuals with high education, income, and wealth.

CONCLUSIONS

The highest level of purpose appeared protective against all-cause mortality regardless of the levels of SES. By contrast, when levels of purpose were more modest, people with lower SES may benefit less health-wise from having a purpose.

Interaction between genetic predisposition, smoking, and dementia risk: a population-based cohort study

We evaluated whether the association between cigarette smoking and dementia risk is modified by genetic predisposition including apolipoprotein E (APOE) genotype and polygenic risk (excluding the APOE region). We included 193,198 UK Biobank participants aged 60-73 years without dementia at baseline. Of non-APOE-ε4 carriers, 0.89% (95% CI 0.73-1.08%) current smokers developed dementia compared with 0.49% (95% CI 0.44-0.55%) of never smokers (adjusted HR 1.78; 95% CI 1.39-2.29). In contrast, of one APOE-ε4 allele carriers, 1.69% (95% CI 1.31-2.12%) current smokers developed dementia compared with 1.40% (95% CI 1.25-1.55%) of never smokers (adjusted HR 1.06; 95% CI 0.77-1.45); of two APOE-ε4 alleles carriers, 4.90% (95% CI 2.92-7.61%) current smokers developed dementia compared with 3.87% (95% CI 3.11-4.74%) of never smokers (adjusted HR 0.94; 95% CI 0.49-1.79). Of participants with high polygenic risk, 1.77% (95% CI 1.35-2.27%) current smokers developed dementia compared with 1.05% (95% CI 0.91-1.21%) of never smokers (adjusted HR 1.63; 95% CI 1.16-2.28). A significant interaction was found between APOE genotype and smoking status (P = 0.002) while no significant interaction was identified between polygenic risk and smoking status (P = 0.25). APOE genotype but not polygenic risk modified the effect of smoking on dementia risk.

Estimating and characterizing the burden of multimorbidity in the community: A comprehensive multistep analysis of two large nationwide representative surveys in France

BACKGROUND

Given the increasing burden of chronic conditions, multimorbidity is now a priority for healthcare and public health systems worldwide. Appropriate methodological approaches for assessing the phenomenon have not yet been established, resulting in inconsistent and incomplete descriptions. We aimed to estimate and characterize the burden of multimorbidity in the adult population in France in terms of number and type of conditions, type of underlying mechanisms, and analysis of the joint effects for identifying combinations with the most deleterious interaction effects on health status.

METHODS AND FINDINGS

We used a multistep approach to analyze cross-sectional and longitudinal data from 2 large nationwide representative surveys: 2010/2014 waves of the Health, Health Care, and Insurance Survey (ESPS 2010-2014) and Disability Healthcare Household Survey 2008 (HSM 2008), that collected similar data on 61 chronic or recurrent conditions. Adults aged ≥25 years in either ESPS 2010 (14,875) or HSM 2008 (23,348) were considered (participation rates were 65% and 62%, respectively). Longitudinal analyses included 7,438 participants of ESPS 2010 with follow-up for mortality (97%) of whom 3,798 were reinterviewed in 2014 (52%). Mortality, activity limitation, self-reported health, difficulties in activities/instrumental activities of daily living, and Medical Outcomes Study Short-Form 12-Item Health Survey were the health status measures. Multiple regression models were used to estimate the impact of chronic or recurrent conditions and multimorbid associations (dyads, triads, and tetrads) on health status. Etiological pathways explaining associations were investigated, and joint effects and interactions between conditions on health status measures were evaluated using both additive and multiplicative scales. Forty-eight chronic or recurrent conditions had an independent impact on mortality, activity limitations, or perceived heath. Multimorbidity prevalence varied between 30% (1-year time frame) and 39% (lifetime frame), and more markedly according to sex (higher in women), age (with greatest increases in middle-aged), and socioeconomic status (higher in less educated and low-income individuals and manual workers). We identified various multimorbid combinations, mostly involving vasculometabolic and musculoskeletal conditions and mental disorders, which could be explained by direct causation, shared or associated risk factors, or less frequently, confounding or chance. Combinations with the highest health impacts included diseases with complications but also associations of conditions affecting systems involved in locomotion and sensorial functions (impact on activity limitations), and associations including mental disorders (impact on perceived health). The interaction effects of the associated conditions varied on a continuum from subadditive and additive (associations involving cardiometabolic conditions, low back pain, osteoporosis, injury sequelae, depression, and anxiety) to multiplicative and supermultiplicative (associations involving obesity, chronic obstructive pulmonary disease, migraine, and certain osteoarticular pathologies). Study limitations included self-reported information on chronic conditions and the insufficient power of some analyses.

CONCLUSIONS

Multimorbidity assessments should move beyond simply counting conditions and take into account the variable impacts on health status, etiological pathways, and joint effects of associated conditions. In particular, the multimorbid combinations with substantial health impacts or shared risk factors deserve closer attention. Our findings also suggest that multimorbidity assessment and management may be beneficial already in midlife and probably earlier in disadvantaged groups.

Additive interaction of mid- to late-life depression and cerebrovascular disease on the risk of dementia: a nationwide population-based cohort study

Background

Dementia is a progressive neurocognitive disease with a substantial social burden. No apparent breakthroughs in treatment options have emerged so far; thus, disease prevention is essential for at-risk populations. Depression and cerebrovascular disease (CVD) are independent risk factors for dementia, but no studies have examined their interaction effect on dementia risk. This study aimed to identify the association of depression and CVD with the risk of dementia and evaluate whether dementia risk among patients with comorbid depression and CVD is higher than the sum of the individual risk due to each condition.

Methods

A population-based cohort study was conducted to analyze the Korean National Health Insurance Service-National Sample Cohort data of all individuals over 50 years of age. Individuals who had not been diagnosed with dementia at baseline were included and followed up from January 1, 2005, to December 31, 2013. A time-varying Cox proportional hazard regression model adjusted for potential confounding factors was used for the analysis. The interaction between depression and CVD was estimated based on the attributable proportion (AP), relative excess risk due to interaction (RERI), synergy index (SI), and multiplicative-scale interaction.

Results

A total of 242,237 participants were included in the analytical sample, of which 12,735 (5.3%) developed dementia. Compared to that for participants without depression or CVD, the adjusted hazard ratio for the incidence of dementia for those with depression alone was 2.35 (95% confidence interval [CI] 2.21–2.49), CVD alone was 3.25 (95% CI 3.11–3.39), and comorbid depression and CVD was 5.02 (95% CI 4.66–5.42). The additive interaction between depression and CVD was statistically significant (AP—0.08, 95% CI 0.01–0.16; RERI—0.42, 95% CI 0.03–0.82; SI—1.12, 95% CI 1.01–1.24). The multiplicative interaction was significant too, but the effect was negative (0.66, 95% CI 0.60–0.73).

Conclusions

In this population-based nationwide cohort with long-term follow-up, depression and CVD were associated with an increased risk of dementia, and their coexistence additively increased dementia risk more than the sum of the individual risks.

Mining Complex Genetic Patterns Conferring Multiple Sclerosis Risk

(1) Background: Complex genetic relationships, including gene-gene (G × G; epistasis), gene(n), and gene-environment (G × E) interactions, explain a substantial portion of the heritability in multiple sclerosis (MS). Machine learning and data mining methods are promising approaches for uncovering higher order genetic relationships, but their use in MS have been limited. (2) Methods: Association rule mining (ARM), a combinatorial rule-based machine learning algorithm, was applied to genetic data for non-Latinx MS cases (n = 207) and controls (n = 179). The objective was to identify patterns (rules) amongst the known MS risk variants, including HLA-DRB1*15:01 presence, HLA-A*02:01 absence, and 194 of the 200 common autosomal variants. Probabilistic measures (confidence and support) were used to mine rules. (3) Results: 114 rules met minimum requirements of 80% confidence and 5% support. The top ranking rule by confidence consisted of HLA-DRB1*15:01, SLC30A7-rs56678847 and AC093277.1-rs6880809; carriers of these variants had a significantly greater risk for MS (odds ratio = 20.2, 95% CI: 8.5, 37.5; p = 4 × 10⁻⁹). Several variants were shared across rules, the most common was INTS8-rs78727559, which was in 32.5% of rules. (4) Conclusions: In summary, we demonstrate evidence that specific combinations of MS risk variants disproportionately confer elevated risk by applying a robust analytical framework to a modestly sized study population.

Tutorial: A nontechnical explanation of the counterfactual definition of effect modification and interaction

Effect modification and interaction are important concepts for answering causal questions about interdependent effects of two (or more) exposures on some outcome of interest. Although conceptually alike and often mistakenly regarded as synonymous, effect modification and interaction actually refer to slightly different concepts when considered from a causal perspective. Their subtle yet relevant distinction lies in how the interplay between exposures is defined and the causal roles attributed to the exposures involved in the effect modification and interaction. To gain more insight into similarities and differences between the concepts of effect modification and interaction, the counterfactual theory of causation, albeit complicated, can be very helpful. Therefore, this article presents a nontechnical explanation of the counterfactual definition of effect modification and interaction. Essentially, effect modification and interaction are reflections of the reality and complexity of multicausality. The causal effect of an exposure of interest often depends on the levels of other exposures (effect modification) or causal effects of other exposures (interaction). Consequently, exposure effects should not be regarded in isolation but in combination. Understanding the underlying principles of effect modification and interaction on a conceptual level enables researchers to better anticipate, detect, and interpret these causal phenomena when setting up, analyzing, and reporting findings of (clinical) epidemiological studies. Effect modification and interaction are not biases to be avoided but properties of causal effects that ought to be unveiled. Hence, evidence for effect modification and interaction needs to be shown in order to delineate in whom and which instances causal effects occur.

Interaction Between GAD65 Antibodies and Dietary Fish Intake or Plasma Phospholipid n-3 Polyunsaturated Fatty Acids on Incident Adult-Onset Diabetes: The EPIC-InterAct Study

OBJECTIVE

Islet autoimmunity is associated with diabetes incidence. We investigated whether there was an interaction between dietary fish intake or plasma phospholipid n-3 polyunsaturated fatty acid (PUFA) concentration with the 65-kDa isoform of GAD (GAD65) antibody positivity on the risk of developing adult-onset diabetes.

RESEARCH DESIGN AND METHODS

We used prospective data on 11,247 incident cases of adult-onset diabetes and 14,288 noncases from the EPIC-InterAct case-cohort study conducted in eight European countries. Baseline plasma samples were analyzed for GAD65 antibodies and phospholipid n-3 PUFAs. Adjusted hazard ratios (HRs) for incident diabetes in relation to GAD65 antibody status and tertiles of plasma phospholipid n-3 PUFA or fish intake were estimated using Prentice-weighted Cox regression. Additive (proportion attributable to interaction [AP]) and multiplicative interactions between GAD65 antibody positivity (≥65 units/mL) and low fish/n-3 PUFA were assessed.

RESULTS

The hazard of diabetes in antibody-positive individuals with low intake of total and fatty fish, respectively, was significantly elevated (HR 2.52 [95% CI 1.76-3.63] and 2.48 [1.79-3.45]) compared with people who were GAD65 antibody negative and had high fish intake, with evidence of additive (AP 0.44 [95% CI 0.16-0.72] and 0.48 [0.24-0.72]) and multiplicative (P = 0.0465 and 0.0103) interactions. Individuals with high GAD65 antibody levels (≥167.5 units/mL) and low total plasma phospholipid n-3 PUFAs had a more than fourfold higher hazard of diabetes (HR 4.26 [2.70-6.72]) and an AP of 0.46 (0.12-0.80) compared with antibody-negative individuals with high n-3 PUFAs.

CONCLUSIONS

High fish intake or relative plasma phospholipid n-3 PUFA concentrations may partially counteract the increased diabetes risk conferred by GAD65 antibody positivity.

Direct and indirect effects of marijuana use on the risk of fatal 2-vehicle crash initiation

BACKGROUND

Marijuana and alcohol each play a significant role in fatal crash initiation. We decomposed the total effect of marijuana use in the presence or absence of alcohol on fatal crash initiation into direct and indirect effects.

METHODS

Pair-matched data on 5856 culpable drivers (initiators) and 5856 nonculpable drivers (noninitiators) involved in the same fatal 2-vehicle crashes recorded in the Fatality Analysis Reporting System between 2011 and 2016 were analyzed using the conditional logistic regression model and the unified mediation and interaction analysis framework.

RESULTS

Crash initiators were more likely than noninitiators to test positive for marijuana (16.1% vs. 9.2%, P < 0.001), alcohol (28.6% vs. 9.7%, P < 0.001) and both substances (6.3% vs. 1.6%, P < .0001). Adjusted odds ratios of fatal 2-vehicle crash initiation revealed a positive interaction on the additive scale between marijuana and alcohol. Of the total effect of marijuana use on fatal 2-vehicle crash initiation, 68.8% was attributable to the direct effect (51.5% to controlled direct effect and 17.3% to reference interaction effect with alcohol) and 31.2% to the indirect effect (7.8% to mediated interaction effect and 23.4% to pure indirect effect through alcohol).

CONCLUSION

Our results indicate that the increased odds of fatal 2-vehicle crash initiation associated with marijuana use is due mainly to the direct effect.