Letter to the Editor: Comment on "Maternal exposure to air pollution and risk of autism in children: A systematic review and meta-analysis"

The influence of burnout on cardiovascular disease: a systematic review and meta-analysis

Background

Burnout is a public health problem with various health consequences, among which cardiovascular disease is the most investigated but still under debate. Our objective was to conduct a systematic review and meta-analysis on the influence of burnout on cardiovascular disease.

Methods

Studies reporting risk (odds ratio, relative risk, and hazard ratio) of cardiovascular disease following burnout were searched in PubMed, PsycINFO, Cochrane, Embase, and ScienceDirect. We performed a random-effect meta-analysis stratified by type of cardiovascular disease and searched for putative influencing variables. We performed sensitivity analyses using the most adjusted models and crude risks.

Results

We included 25 studies in the systematic review and 9 studies in the meta-analysis (4 cross-sectional, 4 cohort, and 1 case-control study) for a total of 26,916 participants. Burnout increased the risk of cardiovascular disease by 21% (OR = 1.21, 95% CI 1.03 to 1.39) using the most adjusted risks and by 27% (OR = 1.27, 95% CI 1.10 to 1.43) using crude risks. Using stratification by type of cardiovascular disease and the most adjusted risks, having experienced burnout significantly increased the risk of prehypertension by 85% (OR = 1.85, 95% CI 1.00 to 2.70) and cardiovascular disease-related hospitalization by 10% (OR = 1.10, 95% CI 1.02 to 1.18), whereas the risk increase for coronary heart disease (OR = 1.79, 95% CI 0.79 to 2.79) and myocardial infarction (OR = 1.78, 95% CI 0.85 to 2.71) was not significant. Results were also similar using crude odds ratio. The risk of cardiovascular disease after a burnout was not influenced by gender. Insufficient data precluded other meta-regressions.

Conclusions

Burnout seems to increase the risk of cardiovascular disease, despite the few retrieved studies and a causality weakened by cross-sectional studies. However, numerous studies focused on the pathophysiology of cardiovascular risk linked to burnout, which may help to build a preventive strategy in the workplace.

Autism spectrum disorder and air pollution: A systematic review and meta-analysis

Despite the widely-known effects of air pollution, pollutants exposure surrounding pregnancy and the risk for autism spectrum disorder (ASD) in newborns remains controversial. The purpose of our study was to carry out a systematic review and meta-analyses of the risk of ASD in newborns following air pollution exposure during the perinatal period (preconception to second year of life). The PubMed, Cochrane Library, Embase and ScienceDirect databases were searched for articles, published up to July 2020, with the keywords "air pollution" and "autism". Three models were used for each meta-analysis: a global model based on all risks listed in included articles, a pessimistic model based on less favorable data only, and an optimistic model based on the most favorable data only. 28 studies corresponding to a total of 758 997 newborns were included (47190 ASD and 703980 controls). Maternal exposure to all pollutants was associated with an increased risk of ASD in newborns by 3.9% using the global model and by 12.3% using the optimistic model, while the pessimistic model found no change. Each increase of 5 μg/m³ in particulate matter <2.5 μm (PM2.5) was associated with an increased risk of ASD in newborns, regardless of the model used (global +7%, pessimistic +5%, optimistic +15%). This risk increased during preconception (global +17%), during pregnancy (global +5%, and optimistic +16%), and during the postnatal period (global +11% and optimistic +16%). Evidence levels were poor for other pollutants (PM10, NOx, O3, metals, solvents, styrene, PAHs, pesticides). PM2.5 was associated with a greater risk than PM10 (coefficient 0.20, 95CI -0.02 to 0.42), NOx (0.29, 0.08 to 0.50) or solvents (0.24, 0.04 to 0.44). All models revealed that exposure to pollutants, notably PM2.5 during pregnancy, was associated with an increased risk of ASD in newborns. Pregnancy and postnatal periods seem to be the most at-risk periods.