Long-term night shift work, genetic predisposition, and risk of incident asthma: a prospective cohort study.

BACKGROUND: Evidence about a potential link between current and lifetime night shift work and risk of incident asthma is insufficient.

AIM: To investigate the association of current and lifetime night shift work with risk of incident asthma, and the modified effect of genetic susceptibility on this association.

DESIGN AND METHODS: We included 253,773 individuals with complete night shift work information in the UK biobank. We calculated the standard polygenetic risk score (PRS) for asthma. The Cox proportional hazard models were conducted to estimate hazard ratios (HRs) and 95% CIs.

RESULTS: After multivariable adjustments, we found that current night shift work was associated with an increased risk of incident asthma in a dose-response fashion (P for trend<0.001). Compared with day workers, those working usual/permanent night shifts had a 17% (95% CI: 1.04-1.33) higher risk of asthma incidence. In addition, we observed significant dose-dependent relationships of longer lifetime duration or frequency of night shift work with elevated risk of asthma incidence (all P for trend<0.05). Compared with never night shift workers, those with a duration (≥5 years) or frequency (≥8 nights/month) of night shift work exhibited a 20% (95% CI: 1.03-1.39) or 22% (95% CI: 1.03-1.44) higher risk of incident asthma, respectively. Moreover, the elevated risk of incident asthma related to current and lifetime night shift work exposure was strengthened by high PRS, although no significant shift work-PRS interactions were detected.

CONCLUSION: Both current and lifetime night shift work may increase the risk of incident asthma, regardless of genetic predisposition to asthma.