Association between long working hours and estimated glomerular filtration rate in health care workers: a retrospective cohort study

Introduction
The impact of long working hours on early chronic kidney disease (CKD) remains uncertain. This study aimed to investigate the association between long working hours and estimated glomerular filtration rate (eGFR) in healthcare workers.

Methods
A retrospective cohort study was conducted among healthcare workers at a tertiary medical center in Taiwan from 2002 to 2021. Eligible participants included all hospital employees aged 20 to 65 with complete working hour records and a yearly blood test of eGFR. Those with eGFR <60 ml/min/1.73 m² at enrollment were excluded. Total working hours and night working hours were recorded for each year. The relationship between total working hours, night working hours and eGFR was assessed using the generalized linear mixed model (GLMM), adjusting for demographic and laboratory profiles.

Results
A total of 10,358 participants with a mean age of 26.7 years (standard deviation 7.1) were included, with 88.9% being females. The median follow-up period was 4 years. Each 10-hour increase in weekly working hours was associated with a decrease in eGFR by -2.07 (-2.99, -1.14). Factors such as age, diastolic blood pressure, glucose, uric acid, and male sex were also linked to lower eGFR. The effect of a 10-hour increase in weekly working hours on eGFR was nearly 1.2 times that of each year increase in age.

Discussion and conclusion
This study reveals a significant association between long working hours and lower eGFR among healthcare workers. These findings suggest that regulating working hours may be a potential strategy to impede the progression of early chronic kidney disease.