Long-Term Exposure to Low-Level PM2.5 and Mortality: Investigation of Heterogeneity by Harmonizing Analyses in Large Cohort Studies in Canada, United States, and Europe.

BACKGROUND: Studies across the globe generally reported increased mortality risks associated with particulate matter with aerodynamic diameter ≤2.5µm (PM2.5) exposure with large heterogeneity in the magnitude of reported associations and the shape of concentration-response functions (CRFs). We aimed to evaluate the impact of key study design factors (including confounders, applied exposure model, population age, and outcome definition) on PM2.5 effect estimates by harmonizing analyses on three previously published large studies in Canada [Mortality-Air Pollution Associations in Low Exposure Environments (MAPLE), 1991-2016], the United States (Medicare, 2000-2016), and Europe [Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE), 2000-2016] as much as possible. METHODS: We harmonized the study populations to individuals 65+ years of age, applied the same satellite-derived PM2.5 exposure estimates, and selected the same sets of potential confounders and the same outcome. We evaluated whether differences in previously published effect estimates across cohorts were reduced after harmonization among these factors. Additional analyses were conducted to assess the influence of key design features on estimated risks, including adjusted covariates and exposure assessment method. A combined CRF was assessed with meta-analysis based on the extended shape-constrained health impact function (eSCHIF). RESULTS: More than 81 million participants were included, contributing 692 million person-years of follow-up. Hazard ratios and 95% confidence intervals (CIs) for all-cause mortality associated with a 5-µg/m3 increase in PM2.5 were 1.039 (1.032, 1.046) in MAPLE, 1.025 (1.021, 1.029) in Medicare, and 1.041 (1.014, 1.069) in ELAPSE. Applying a harmonized analytical approach marginally reduced difference in the observed associations across the three studies. Magnitude of the association was affected by the adjusted covariates, exposure assessment methodology, age of the population, and marginally by outcome definition. Shape of the CRFs differed across cohorts but generally showed associations down to the lowest observed PM2.5 levels. A common CRF suggested a monotonically increased risk down to the lowest exposure level. https://doi.org/10.1289/EHP12141.

Dietary Supplement Use after Cancer Diagnosis in Relation to Total Mortality, Cancer Mortality and Recurrence: A Systematic Review and Meta-Analysis.

To study post-diagnosis dietary supplement use in relation to total mortality, cancer mortality and recurrence among cancer survivors. PubMed and Cochrane Library were searched until April 2019 for observational studies (OS) and randomized clinical trials (RCT). Pooled risk ratios (RR) were calculated using random-effects models. Compared to no supplementation, calcium supplementation was associated with lower total (RR = 0.88, 95% confidence interval (CI): 0.77-1.00, I2=0%, four OS) and cancer mortality (RR = 0.71, 95% CI: 0.53-0.95, I2=0%, three OS) among all cancer survivors, and cancer mortality among colorectal cancer survivors (RR = 0.66, 95% CI: 0.47-0.94, I2=0%, two OS). Vitamin D supplementation was associated with lower total mortality (RR = 0.86, 95% CI: 0.76-0.99, I2=0%, three OS and two RCT). Among breast cancer survivors, supplementation with vitamin C (RR = 0.79, 95% CI: 0.68-0.92, I2=0%, four OS), D (RR = 0.85, 95% CI: 0.72-0.99, I2=0%, two OS), and E (RR = 0.76, 95% CI: 0.64-0.90, I2=0%, three OS) was associated with lower total mortality, while multivitamins (RR = 0.79, 95% CI: 0.64-0.97, I2=0%, two OS), vitamin C (RR = 0.76, 95% CI: 0.64-0.91, I2=0%, two OS), and E (RR = 0.69, 95% CI: 0.55-0.85, I2=0%, two OS) with lower cancer recurrence. Conclusions: Findings are mostly based on OS. More RCTs are needed to justify any recommendation for use.