Shift Work is Associated with an Elevated White Blood Cell Count: A Systematic Review and Meta-Analysis

The effect of shift work on different hematological parameters among healthcare workers

Shift workers frequently experience alterations in their circadian rhythms, which are correlated with variations in hematological parameters. Changes in blood cells may be related to an individual's health status. Therefore, this study aimed to compare the relationship between shift work and changes in blood cells among a group of healthcare workers in Sri Lanka. A comparative cross-sectional study was conducted among healthcare workers, recruited by a stratified random sampling technique. Socio-demographic data were collected using a structured questionnaire. Venous blood samples were obtained and analyzed for the determination of total and differential blood cell counts. Descriptive statistics were used for the analysis of sociodemographic and hematological parameters. A sample of 37-day workers and 39 shift workers were included in the analysis. The mean ages (years) were not significantly different between the groups (36.8 ± 10.8 vs 39.1 ± 12.0; P = 0.371). Shift employees showed a significantly higher total mean white blood cell count (WBC) of 7548.75 mm-3 compared to day workers' 6869.19 mm-3 (P = 0.027). They also had higher mean absolute counts for all different WBC types (Neutrophils: 3949.2 vs 3557.7  , Lymphocyte: 2756.5 vs 2614.2  , Eosinophil: 317.6 vs 233.4  , Monocytes: 491.63 vs 432.51  , Basophils: 31.68 vs 29.22  ). Shift employees exhibited higher WBC counts than day workers at the same level of work experience. The length of shift work exposure revealed a positive link with neutrophil (r = 0.225  ) and eosinophil counts (r = 0.262  ), whereas these correlations were negative for day workers. Shift workers were associated with higher WBC counts in healthcare workers compared to their day-working counterparts.