Salivary Cortisol Concentrations, Grit, and the Effect of Time

Stress is a common experience in the emergency department (ED) and is a balance of personal capabilities versus demands. Residency training is meant to improve individuals' capabilities and therefore may attenuate an individual's stress response. Grit is a personality trait that may attenuate stress in individuals. In this study we explore the relationship between time of year, postshift salivary cortisol concentrations, and the influence of grit among attendings and residents in an academic ED.

Thirty-nine residents and 17 attendings were enrolled and followed for two academic years at an urban academic medical center. Postwork salivary cortisol samples were collected quarterly, and Duckworth 12-point Grit Scales were administered annually. Data from the relative quarters of the first and second years were combined, and the results were analyzed using descriptive statistics and generalized estimating equations.

We analyzed 216 cortisol samples and 87 grit scores over 2 academic years. Between the first and fourth quarters of the academic year, the percentage of subjects with a detectable postshift cortisol sample decreased from 47.6% (30 of 62) to 18.4% (9 of 49). In the fourth academic quarter compared to the first, the odds that an individual had a detectable cortisol were significantly lower overall (odds ratio [OR] = 0.25, 95% confidence interval [CI] = 0.10 to 0.59, p = 0.01), including the subset of only trainees (OR = 0.26, 95% CI = 0.07 to 0.88, p = 0.01), and adjusting for grit did not meaningfully change the ORs.

Over the course of the academic year, the odds that an individual's postshift salivary cortisol concentration will be above detectable concentration significantly decrease over time, and this relationship is not confounded by grit.