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

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. 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). Mean age was 46 years (SD = 6.6). After adjustment for potential confounders, there was a significant inverse association between ERI and peak cortisol (beta = - 0.20, p = 0.009), average cortisol (beta = - 0.23, p = 0.003), and total area under the curve (beta = - 0.21, p = 0.009). ERI was not significantly associated with AUCI (beta = - 0.11, p = 0.214); slope of the regression line fitted to the cortisol profile (beta = - 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). ERI was inversely associated with the magnitude of awakening cortisol over time, indicating HPA axis dysregulation and potential future health outcomes.