Working hours, on‐call shifts, and risk of occupational injuries among hospital physicians: A case‐crossover study

OBJECTIVE: To investigate the association of hospital physicians’ working hours and on‐call shifts with the risk of occupational injuries. METHODS: In this nested cohort study of 556 Finnish hospital physicians, we linked electronic records from working‐hour and on‐call duty payroll data to occupational injury data obtained from the Finnish Workers’ Compensation Center for the period 2005–2019. We used a case‐crossover design with matched intervals for a 7‐day ‘case window’ immediately prior to occupational injury and a ‘control window’ 7 days prior to the beginning of the case window, and analyzed their associations using conditional logistic regression models. RESULTS: We noted 556 occupational injuries, 281 at the workplace and 275 while commuting. Having three to four long (>12 h) work shifts on the preceding 7 days was associated with a higher probability of an occupational injury (odds ratio [OR] 2.14, 95% confidence interval [CI] 1.11, 4.09), and the OR for three to four on‐call shifts was 3.54 (95%CI 2.11, 5.92) in comparison to having none of these work shift types. A higher number of several consecutive working days was associated with a higher probability of injury in a dose‐response manner. Moreover, increasing weekly working hours was associated with an increased likelihood of injury (OR 1.03, 95%CI 1.01, 1.04), whereas the number of normal (≤12 h) work shifts reduced this likelihood (OR 0.79, 95%CI 0.64, 0.98). CONCLUSIONS: Our findings suggest that accumulated working‐hour load, as opposed to single, very long (>24 h) work shifts, may increase the risk of occupational injury among hospital physicians.