Salivary Cortisol and Anxiety in Canadian Dentists over 1 Year of COVID-19

Abstract

The dental profession has endured unprecedented disruption amid COVID-19. Novel stressors have included a high risk of occupational exposure to COVID-19, financial losses, and stricter infection prevention and control requirements. The present study investigated the longitudinal impact of COVID-19 on the stress and anxiety levels of a cohort of Canadian dentists (N = 222) between September 2020 and October 2021. Salivary cortisol was selected as a biomarker of mental stress, and 10 sets of monthly saliva samples (2,131 in total) were self-collected, sent to our laboratory in prepaid courier envelopes, and analyzed by enzyme-linked immunosorbent assay. To assess COVID-19 anxiety, 9 monthly online questionnaires were administered, comprising a general COVID-19 anxiety instrument and 3 items regarding the impact of dentistry-related factors. Bayesian log-normal mixed effect models were fitted to estimate the longitudinal trajectory of salivary cortisol levels and their association with the disease burden of COVID-19 in Canada. After accounting for age, sex, vaccination status, and the diurnal rhythm of cortisol secretion, a modest positive association was found between dentists' salivary cortisol levels and the count of COVID-19 cases in Canada (96% posterior probability). Similarly, the self-reported impact of dentistry-related factors, such as fear of getting COVID-19 from a patient or coworker, was greatest during peaks of COVID-19 waves in Canada; however, general COVID-19 anxiety decreased consistently throughout the study period. Interestingly, at all collection points, the majority of participants were not concerned about personal protective equipment. Overall, participants reported relatively low rates of psychological distress symptoms in relation to COVID-19, a result that should be reassuring for the dental community. Our findings strongly suggest a link between self-reported and biochemical measurements of stress and anxiety in Canadian dentists during the COVID-19 pandemic.

Keywords: biomarkers; pandemic; personal protective equipment; psychological distress; saliva; self report.

Figure 1.

Diurnal rhythm of salivary cortisol (μg/dL) in all samples acquired during the study period, estimated via a bayesian log-normal mixed effect model. Light blue shading represents the 95% credible interval. Our data demonstrate a typical diurnal rhythm with a peak around 7 am and a steady decrease over the course of the day.

Figure 2.

A modest positive association was observed between the average trajectory of dentists’ salivary cortisol levels (μg/dL) and the count of COVID-19 cases in Canada (96% posterior probability). Vertical lines represent important milestones during the COVID-19 pandemic in Canada. (A) A bayesian log-normal mixed effect model was used to estimate the average trajectory of salivary cortisol levels throughout the study period. Light blue shading represents the 95% credible interval. (B) Count of COVID-19 cases in Canada (7-d moving average) during the study period, re-created with data from https://healthinfobase.canada.ca/covid-19/. Note that salivary cortisol levels peaked in January and September 2021, in accordance with the peaks of the second and fourth waves of COVID-19 in Canada. However, there was a high degree of variability in salivary cortisol levels.

Figure 3.

(A–C) Self-reported impact of dentistry-related factors among a cohort of Canadian dentists. Participants were asked to rate their experiences during the past 2 wk on a 5-point time-anchored scale (0 = not at all, 4 = nearly every day). Each vertical column represents the responses provided during a single collection point. (D) Count of COVID-19 cases in Canada (7-d moving average) during the study period, re-created with data from https://health-infobase.canada.ca/covid-19/. For all 3 dentistry-related factors, the proportion of participants reporting at least some degree of impact peaked in January, April, and September 2021. The timing of these peaks corresponds with that of the second, third, and fourth waves of COVID-19 in Canada.

Figure 4.

Average trajectory of general COVID-19 anxiety scores stratified by sex. Participants were asked to consider their experiences during the past 2 wk and rate COVID-19 Anxiety Syndrome Scale items on a 5-point time-anchored scale (0 = not at all, 4 = nearly every day). Green and blue shading represents the 95% credible interval for female and male participants, respectively. (A) Avoidance factor (range of possible scores, 0 to 12). (B) Perseveration factor (range of possible scores, 0 to 24). Note that both perseveration and avoidance scores consistently decreased throughout the study period.