Understanding interactions between risk factors, and assessing the utility of the additive and multiplicative models through simulations

Impact of multimorbidity and cognitive impairment on depressive symptoms in community-dwelling older adults and their interaction effects

This study aims to evaluate the independent and interactive effects of multimorbidity and cognitive impairment on depressive symptoms among older adults in China. Employing a cross-sectional design, the study collected data from 10,369 individuals aged 65 and above across 35 communities/villages in China. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9), cognitive function was evaluated with the Alzheimer's Disease-8 (AD-8) scale, and chronic disease conditions were recorded. The results indicated that older adults with multimorbidity (OR = 2.481, 95% CI: 2.117, 2.908) and those at high risk of cognitive impairment (OR = 5.469, 95% CI: 4.644, 6.441) exhibited a higher likelihood of experiencing depressive symptoms. Further interaction analysis revealed that, after controlling for confounding factors, no significant multiplicative interaction was found between multimorbidity and cognitive impairment (P = 0.581); however, a significant additive interaction effect was observed (OR = 13.809, 95% CI: 11.063, 17.237). These findings suggest that multimorbidity and cognitive impairment are important factors associated with depressive symptoms in older adults, and their combined presence is linked to a substantially increased likelihood of experiencing depressive symptoms compared to either condition alone.

Assessing hemorrhagic risks in combination therapy: implications of angiogenesis inhibitors and immune checkpoint inhibitors

Objective

This study aims to evaluate the hemorrhage risk in solid tumor patients receiving angiogenesis inhibitors (AGIs), immune checkpoint inhibitors (ICIs), and their combination using the FDA Adverse Event Reporting System (FAERS) database.

Methods

Data from Q1 2011 to Q4 2023 were extracted from the FAERS database for solid tumor patients treated with AGIs, ICIs, or their combination. A disproportionality analysis was conducted by calculating the reporting odds ratio (ROR) and corresponding 95% confidence interval (CI), as well as the Proportional Reporting Ratio (PRR), to identify potential safety signals. To assess whether the hemorrhage risk is higher with combination therapy compared to monotherapy, additive and multiplicative models were employed to evaluate the interactions between combination and single-agent treatments.

Results

The combination of AGIs and ICIs significantly increased the risk of hemorrhagic adverse events, particularly tumor and pulmonary hemorrhage. Hemorrhagic events were common in females (50.97%) and older patients (aged 64+), frequently occurring within the first 30 days of treatment (38.11%). Gingival hemorrhage (ROR 3, PRR 418.9) and tumor hemorrhage (ROR 9.65, PRR 1893.36) were most common in the AGI group, while tumor hemorrhage (ROR 9.49, PRR 1350.78) and pulmonary hemorrhage (ROR 2.6, PRR 98.97) were prominent in the ICI group. In the combination group, esophageal variceal hemorrhage (ROR 40.72, PRR 2344.72) and tumor hemorrhage (ROR 19.31, PRR 1056.63) exhibited significantly increased risks Additive and multiplicative models indicated that the excess risk (RDAB = 0.01025, P<0.001) and relative risk (RRAB = 1.99277, P<0.001) of combination therapy were significantly higher than those of monotherapy, suggesting a positive interaction between the drugs that further increases the risk of hemorrhage.

Conclusion

Our study demonstrates that the combination of AGIs and ICIs significantly raises the risk of hemorrhage, underscoring the urgent need for enhanced monitoring protocols in clinical practice to improve treatment efficacy and safety.

Association of pre- and post-diagnosis dietary total antioxidant capacity (TAC) and composite dietary antioxidant index (CDAI) with overall survival in patients with ovarian cancer: a prospective cohort study

BACKGROUND

The evidence on the relationship of dietary antioxidant nutrients with the survival of ovarian cancer (OC) remains scarce.

OBJECTIVE

This study aimed to investigate these associations in a prospective cohort of Chinese patients with OC.

METHODS

In this prospective cohort study, patients with epithelial OC completed a food frequency questionnaire at diagnosis and 12 months post-diagnosis, and were followed from 2015 to 2023. Dietary total antioxidant capacity (TAC) and composite dietary antioxidant index (CDAI) were calculated based on specific antioxidant nutrients. We examined the associations of pre-diagnosis, post-diagnosis, and changes from pre-diagnosis to post-diagnosis in TAC, CDAI, and representative antioxidant nutrients with overall survival (OS) among patients with OC. Multivariable Cox proportional-hazards models were applied to calculate the hazard ratios (HR) and 95% confidence intervals (CI). Dose-response relationships were evaluated by restricted cubic splines.

RESULTS

Among the total 560 patients with OC, there were 211 (37.68%) deaths during a median follow-up of 44.40 (interquartile range: 26.97-61.37) months. High pre-diagnosis TAC (HR = 0.58; 95% CI 0.38-0.8) and vitamin C intake (HRT3 vs. T1 = 0.36; 95% CI 0.21-0.61), and post-diagnosis TAC (HR = 0.57; 95% CI 0.37-0.8), CDAI (HR = 0.57; 95% CI 0.33-0.9), and β-carotene intake (HRT3 vs. T1 = 0.55; 95% CI 0.32-0.97) were significantly associated with improved OS. Compared to patients with constantly low pre- and post-diagnosis TAC and CDAI, those with consistently higher TAC (HRMedium-Medium vs. Low-Low = 0.53; 95% CI 0.29-0.97; HRHigh-High vs. Low-Low = 0.40; 95% CI 0.16-0.94) and CDAI (HRHigh-High vs. Low-Low = 0.33; 95% CI 0.12-0.88) experienced better OS.

CONCLUSION

High pre- and post-diagnosis TAC, and post-diagnosis CDAI were associated with improved OC survival, suggesting that consistent high-intake of antioxidant-rich food may be beneficial for the prognosis of OC.

Untangling the independent effect of endometriosis, adenomyosis, and ART-related factors on maternal, placental, fetal, and neonatal adverse outcomes: results from a systematic review and meta-analysis

BACKGROUND

Women with endometriosis may constitute a group at a particularly increased risk of pregnancy-related complications. Furthermore, women selected for assisted reproductive technology (ART) are exposed to additional endocrinological and embryological factors that have been associated with adverse pregnancy outcomes.

OBJECTIVE AND RATIONALE

This study aimed to investigate the independent effect of endometriosis, adenomyosis, and various ART-related factors on adverse maternal, placental, fetal, and neonatal outcomes.

SEARCH METHODS

Published randomized controlled trials, cohort studies, and case-control studies were considered eligible. PubMed, MEDLINE, ClinicalTrials.gov, Embase, and Scopus were systematically searched up to 1 March 2024. This systematic review and meta-analysis was performed in line with the PRISMA and the MOOSE reporting guidelines. To thoroughly investigate the association between endometriosis/adenomyosis and adverse pregnancy outcomes, sub-analyses were conducted, whenever possible, according to: the method of conception (i.e. ART and non-ART conception), the endometriosis stage/phenotype, the coexistence of endometriosis and adenomyosis, any pre-pregnancy surgical treatment of endometriosis, and the form of adenomyosis. The odds ratio (OR) with 95% CI was used as effect measure. The quality of evidence was assessed using the GRADE approach.

OUTCOMES

We showed a higher risk of placenta previa in women with endometriosis compared to controls (34 studies, OR 2.84; 95% CI: 2.47, 3.26; I2 = 83%, moderate quality). The association was observed regardless of the method of conception and was particularly strong in the most severe forms of endometriosis (i.e. rASRM stage III-IV endometriosis and deep endometriosis (DE)) (OR 6.61; 95% CI: 2.08, 20.98; I2 = 66% and OR 14.54; 95% CI: 3.67, 57.67; I2 = 54%, respectively). We also showed an association, regardless of the method of conception, between endometriosis and: (i) preterm birth (PTB) (43 studies, OR 1.43; 95% CI: 1.32, 1.56; I2 = 89%, low quality) and (ii) cesarean section (29 studies, OR 1.52; 95% CI: 1.41, 1.63; I2 = 93%, low quality). The most severe forms of endometriosis were strongly associated with PTB. Two outcomes were associated with adenomyosis both in the main analysis and in the sub-analysis that included only ART pregnancies: (i) miscarriage (14 studies, OR 1.83; 95% CI: 1.53, 2.18; I2 = 72%, low quality) and (ii) pre-eclampsia (7 studies, OR 1.70; 95% CI: 1.16, 2.48; I2 = 77%, low quality). Regarding ART-related factors, the following associations were observed in the main analysis and confirmed in all sub-analyses conducted by pooling only risk estimates adjusted for covariates: (i) blastocyst stage embryo transfer (ET) and monozygotic twinning (28 studies, OR 2.05; 95% CI, 1.72, 2.45; I2 = 72%, low quality), (ii) frozen embryo transfer (FET) and (reduced risk of) small for gestational age (21 studies, OR 0.59; 95% CI, 0.57, 0.61; P < 0.00001; I2 = 17%, very low quality) and (increased risk of) large for gestational age (16 studies, OR 1.70; 95% CI, 1.60, 1.80; P < 0.00001; I2 = 55%, very low quality), (iii) artificial cycle (AC)-FET and pre-eclampsia (12 studies, OR 2.14; 95% CI: 1.91-2.39; I2 = 9%, low quality), PTB (21 studies, OR 1.24; 95% CI 1.15, 1.34; P < 0.0001; I2 = 50%, low quality), cesarean section (15 studies, OR 1.59; 95% CI 1.49, 1.70; P < 0.00001; I2 = 67%, very low quality) and post-partum hemorrhage (6 studies, OR 2.43; 95% CI 2.11, 2.81; P < 0.00001; I2 = 15%, very low quality).

WIDER IMPLICATIONS

Severe endometriosis (i.e. rASRM stage III-IV endometriosis, DE) constitutes a considerable risk factor for placenta previa and PTB. Herein, we recommend against superimposing on this condition other exposure factors that have a strong association with the same obstetric adverse outcome or with different outcomes which, if coexisting, could determine the onset of an ominous obstetric syndrome. Specifically, we strongly discourage the use of AC regimens for FET in ovulatory women with rASRM stage III-IV endometriosis or DE. We also recommend single ET at the blastocyst stage in this high-risk population.

REGISTRATION NUMBER

CRD42023401428.

Identification of an additive interaction using parameter regularization and model selection in epidemiology

Background

In epidemiology, indicators such as the relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy index (S) are commonly used to assess additive interactions between two variables. However, the results of these indicators are sometimes inconsistent in real world applications and it may be difficult to draw conclusions from them.

Method

Based on the relationship between the RERI, AP, and S, we propose a method with consistent results, which are achieved by constraining e θ 3 - e θ 1 - e θ 2 + 1 = 0 , and the interpretation of the results is simple and clear. We present two pathways to achieve this end: one is to complete the constraint by adding a regular penalty term to the model likelihood function; the other is to use model selection.

Result

Using simulated and real data, our proposed methods effectively identified additive interactions and proved to be applicable to real-world data. Simulations were used to evaluate the performance of the methods in scenarios with and without additive interactions. The penalty term converged to 0 with increasing λ, and the final models matched the expected interaction status, demonstrating that regularized estimation could effectively identify additive interactions. Model selection was compared with classical methods (delta and bootstrap) across various scenarios with different interaction strengths, and the additive interactions were closely observed and the results aligned closely with bootstrap results. The coefficients in the model without interaction adhered to a simplifying equation, reinforcing that there was no significant interaction between smoking and alcohol use on oral cancer risk.

Conclusion

In summary, the model selection method based on the Hannan-Quinn criterion (HQ) appears to be a competitive alternative to the bootstrap method for identifying additive interactions. Furthermore, when using RERI, AP, and S to assess the additive interaction, the results are more consistent and the results are simple and easy to understand.

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.

The societal cost of modifiable risk factors in Singapore

BACKGROUND

Singapore is one of the most rapidly ageing populations in the world. Nearly half of all disease burdens in Singapore are attributable to modifiable risk factors. This indicates that many illnesses are preventable by modifying behaviours such as increasing physical activity levels or maintaining a healthy diet. Prior cost-of-illness studies have estimated the cost of selected modifiable risk factors. However, no local study has compared costs between groups of modifiable risks. This study aims to estimate the societal cost attributable to a comprehensive list of modifiable risks in Singapore.

METHODS

Our study builds on the comparative risk assessment framework from the Global Burden of Disease (GBD) 2019 study. A top-down prevalence-based cost-of-illness approach was undertaken to estimate the societal cost of modifiable risks in 2019. These include healthcare costs from inpatient hospitalisation and productivity losses from absenteeism and premature mortality.

RESULTS

Metabolic risks had the highest total cost of US$1.62 billion (95% uncertainty interval [UI] US$1.51-1.84 billion), followed by lifestyle risks of US$1.40 billion (95% UI US$1.36-1.66 billion) and substance risks of US$1.15 billion (95% UI US$1.10-1.24 billion). Across the risk factors, the costs were driven by productivity losses, heavily skewed towards the older working-age group and among males. Most of the costs were driven by cardiovascular diseases.

CONCLUSION

This study provides evidence of the high societal cost of modifiable risks and highlights the importance of developing holistic public health promotion programmes. As modifiable risks often do not occur in isolation, implementing effective population-based programmes targeting multiple modifiable risks has a strong potential to manage the cost of the rising disease burden in Singapore.

Detection and assessment of risk factors associated with Newcastle disease virus infection in birds in backyard poultry in Laichau province of Vietnam

Newcastle disease (ND) is a highly pathogenic and contagious viral infectious disease of poultry that causes a very serious problem for poultry production and economic loss worldwide. ND has been an epizootic disease in Vietnam. Information about the risk factors that are associated with virus transmission in backyard chickens in Vietnam is limited. To provide more epidemiological information about ND in Vietnam, this study was performed to estimate NDV prevalence and identify the risk factors for ND virus (NDV) infection in birds at the backyard flock level. Choanal swabs were taken from 400 randomly selected birds from 100 apparently healthy flocks from May to July 2020. Based on RT-PCR analysis, 43 of 400 swab samples (10.75%; 95% CI 8-14.17) and 21 of 100 flocks (21%; 95% CI 14.17-29.98) were positive for the fusion (F) gene of NDV. The management practice risks were: backyard flocks contacting wild birds (OR = 3.89; P = 0.030), mixed flocks with different types and species of birds (OR = 5.46; P = 0.004), and infrequency of cleaning and disinfecting poultry houses (OR (odds ratio) = 4.43; P = 0.034). The second and third risks (above) showed a positive interaction on the risk of NDV infection in birds (OR = 39.38; P = 0.001), and the first risk showed a negative interaction. Further studies on NDV surveillance in domestic waterfowl, longitudinal studies, a well-optimized RT-qPCR assay, and genetic characterization are needed. The development of handbooks, flyers, or lessons for educating poultry keepers are also needed.RESEARCH HIGHLIGHT RT-PCR was used to detect the F gene of NDV in choanal swabs.Risk factors associated with NDV-positive samples were determined.The evidence for NDV circulation in backyard healthy birds was observed.Contact with wild birds, mixed flocks, and poor hygiene were major risk factors.

Urbanization, air pollution, and water pollution: Identification of potential environmental risk factors associated with amyotrophic lateral sclerosis using systematic reviews

Introduction

Despite decades of research, causes of ALS remain unclear. To evaluate recent hypotheses of plausible environmental factors, the aim of this study was to synthesize and appraise literature on the potential associations between the surrounding environment, including urbanization, air pollution and water pollution, and ALS.

Methods

We conducted a series (n = 3) of systematic reviews in PubMed and Scopus to identify epidemiological studies assessing relationships between urbanization, air pollution and water pollution with the development of ALS.

Results

The combined search strategy led to the inclusion of 44 articles pertaining to at least one exposure of interest. Of the 25 included urbanization studies, four of nine studies on living in rural areas and three of seven studies on living in more highly urbanized/dense areas found positive associations to ALS. There were also three of five studies for exposure to electromagnetic fields and/or proximity to powerlines that found positive associations to ALS. Three case-control studies for each of diesel exhaust and nitrogen dioxide found positive associations with the development of ALS, with the latter showing a dose-response in one study. Three studies for each of high selenium content in drinking water and proximity to lakes prone to cyanobacterial blooms also found positive associations to ALS.

Conclusion

Whereas markers of air and water pollution appear as potential risk factors for ALS, results are mixed for the role of urbanization.

Genetics of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease involving symmetric joints and is generally characterized by persistent pain, tenderness, and destruction of joints. The vast majority of RA patients produce autoantibodies, and immune cell involvement in disease development is well recognized, as is the contribution of other types of cells in synovial tissue, like fibroblasts. It is known that there are major genetic associations with the HLA locus, while multiple non-HLA genetic variants display relatively low risk of RA. Both HLA and non-HLA associations suggest that the profiles of genetic associations for autoantibody-positive vs. autoantibody-negative RA are different. Several alleles of HLA-DRB1 are associated with high risk for autoantibody-positive RA, with the strongest risk characterized by valine at position 11 of the protein sequence (HLA-DRB1*04 and *10 alleles). There is a strong protective effect for the risk of autoantibody-positive RA associated with HLA-DRB1*13 alleles. Although major genetic associations have been known for several years, understanding of the specific mechanisms in the development of increased risk of RA for these variations is work in progress. Current studies focus on the binding of immune receptors involved in recognition of putative peptides in activation of T cells, as well as investigation of cell signaling mechanisms. At least a part of RA risk could be explained by gene-gene and gene-environment interactions. There are currently more than 150 candidate loci with polymorphisms that associate with RA, mainly related to seropositive disease, and new discoveries are anticipated in the future from investigation of diverse human populations. This new research will help create a strong foundation for the continuing process of integrating genetic, epigenetic, transcriptomic, and proteomic data in studies of RA.