Effort–reward imbalance in police work: associations with the cortisol awakening response

Purpose We hypothesized that effort–reward imbalance (ERI) is associated with an atypical cortisol response. ERI has been associated with higher job stress. Stress triggers cortisol secretion via the hypothalamic–pituitary–adrenal (HPA) axis, and significant deviation from a typical cortisol pattern can indicate HPA axis dysfunction. Methods 176 police officers participated from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) Study. ERI was the exposure variable. Outcome variables were saliva-based peak and mean cortisol values, total area under the curve ground (AUCG) and baseline (AUCI); linear regression line fitted to log-transformed cortisol. Regression analyses were used to examine linear trend between ERI and cortisol parameters. Repeated measures analysis examined whether the pattern of cortisol over time differed between low ERI (< median) and high ERI (≥ median). Results Mean age was 46 years (SD = 6.6). After adjustment for potential confounders, there was a significant inverse association between ERI and peak cortisol ( β = − 0.20, p = 0.009), average cortisol ( β = − 0.23, p = 0.003), and total area under the curve ( β = − 0.21, p = 0.009). ERI was not significantly associated with AUCI ( β = − 0.11, p = 0.214); slope of the regression line fitted to the cortisol profile ( β = − 0.009, p = 0.908). Repeated measures analyses showed that the cortisol pattern did not vary significantly between high and low ERI using the median as a cut point (interaction p value = 0.790). Conclusions ERI was inversely associated with the magnitude of awakening cortisol over time, indicating HPA axis dysregulation and potential future health outcomes.