Link between night-shift exposure, CVD stronger in workers with cardiovascular susceptibility

Night-shift exposure is significantly associated with incident cardiovascular disease (CVD) among workers, and this association is most pronounced among those with greater baseline cardiovascular vulnerability, suggests a study.

A total of 85,322 UK Biobank participants with occupational night-shift information were included in the analysis. Baseline CVD risk profile was classified as low, intermediate, or high using a composite score based on CVD polygenic risk score tertiles, current smoking, obesity, low moderate-to-vigorous physical activity, and insomnia.

The authors assessed night-shift exposure in two ways—monthly intensity and yearly duration—each categorized as none, low, or high. They also identified incident CVD from inpatient records and explored associations using Cox proportional hazards models.

Of the participants, 24,696 had low CVD risk, 49,332 had intermediate risk, and 11,294 had high risk. Across all strata, workers with no night-shift exposure showed the lowest incidence of CVD. In the low-risk group, high monthly intensity and high yearly duration each correlated with similarly elevated risk, which was more noticeable in the high-risk group.

With regard to monthly intensity, the low-intensity group had a 35-percent higher CVD risk (adjusted hazard ratio [aHR], 1.35, 95 percent confidence interval [CI], 1.19‒1.52), while the high-intensity group had a 22-percent increased risk (aHR, 1.22, 95 percent CI, 1.08‒1.37). For yearly duration, the corresponding aHRs were 1.21 (95 percent CI, 1.06‒1.37) and 1.34 (95 percent CI, 1.19‒1.51).

“Compared with monthly intensity, yearly duration showed a more consistent exposure-response pattern,” the authors said.