Objective This study aimed to determine if there is an increased risk of incident cardiovascular diseases (CVD) resulting from cumulative night shift work in the German population-based Gutenberg Health Study (GHS).

Methods We examined working participants of the GHS at baseline and after five years. Cumulative night shift work in the 10 years before baseline was assessed and categorized as low (1–220 nights ≙ up to 1 year), middle (221–660 nights ≙ 1–3 years), and high (>660 nights ≙ more than 3 years) night shift exposure. Hazard ratios (HR) were estimated for incident “quality-assured CVD events” using Cox proportional hazard models.

Results At baseline, 1092 of 8167 working participants performed night shift work. During the follow-up, 202 incident cardiovascular events occurred. The crude incidence rates for CVD per 1000 person-years were 6.88 [95% confidence interval (CI) 4.80–9.55] for night shift workers and 5.19 (95% CI 4.44–6.04) for day workers. Cumulative incidence curves showed a higher cumulative incidence in workers exposed to night shift work compared to day workers after five years. The adjusted HR for incident CVD events were 1.26 (95% CI 0.68–2.33), 1.37 (95% CI 0.74–2.53) and 1.19 (95% CI 0.67–2.12) for employees in the low, middle and high night shift categories compared to employees without night shift work, respectively.

Conclusions The observed tendencies indicate that night shift work might be negatively associated with cardiovascular health. We expect the continued follow-up will clarify the long-term impact of night shift work.

Key terms cardiovascular disease; cohort study; CVD; employee; Germany; GHS; Gutenberg Health Study; incidence; longitudinal study; night shift; occupation; population-based; Rhineland-Palatinate; shift work; workplace

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