The performance of marginal structural models for estimating risk differences and relative risks using weighted univariate generalized linear models
Austin PC. Stat Methods Med Res. 2024; Apr 24 [Epub ahead of print].
Background — Despite recent studies linking air pollution to neurodegenerative illness, evidence relating air pollution and Parkinson’s disease (PD) remains scarce. We conducted a population-based cohort study in Ontario, Canada, to determine the association between air pollution and incident PD.
Methods — Using health administrative databases, we identified all adults aged 55–85 years, free of PD, and who lived in Ontario on 1 April 2001 (∼2.2 million). Individuals were followed up until 31 March 2013. We derived long-term average exposures to fine particulate matter (particles ≤2.5 µm in diameter, or PM2.5), nitrogen dioxide (NO2) and ozone from satellite-based estimates, land-use regression models and optimal interpolation methods, respectively. Using 2-year lags in exposures, we linked these estimates to individuals’ annual postal codes from 1994 (7 years before cohort inception). We applied spatial random-effects Cox proportional hazards models, adjusting for individual- and area-level characteristics. We also performed sensitivity analyses, such as considering longer lags in exposures and stratifying by selected characteristics.
Results — During the study period, we identified 38 745 newly diagnosed cases of PD. Each interquartile increment (3.8 µg/m3) of PM2.5 was associated with a 4% increase in incident PD (95% confidence interval, 1.01–1.08) after adjusting for various covariates. We also found positive associations for NO2 and ozone [hazard ratios (HRs) ranged from 1.03 to 1.04]. The associations for all exposures were unaltered with various sensitivity analyses except for considering longer lags, which somewhat attenuated the estimates, particularly for NO2 and ozone.
Conclusions — Exposure to air pollution, especially PM2.5, was found to be related to incident PD.
Shin S, Burnett RT, Kwong JC, Hystad P, van Donkelaar A, Brook JR, Copes R, Tu K, Goldberg MS, Villeneuve PJ, Martin RV, Murray BJ, Wilton AS, Kopp A, Chen H. Int J Epidemiol. 2018; 47(6):2038-48. Epub 2018 Aug 16.
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