Depression among physicians has significant personal and professional implications. Exposure to stressful work environments is hypothesized to trigger depression.1 Intensity of training, long work hours, and high levels of persistent mistreatment may put surgical interns at particularly high risk.2 We present herein estimates of new-onset depression among surgical interns.
Data on US-based interns originated from the Intern Health Study, a sequential, prospective, annual cohort study evaluating physician mental health among interns. The Intern Health Study collected written informed consent and was approved by the institutional review board of the University of Michigan, Ann Arbor. This study followed the STROBE reporting guideline.
Sex and race and ethnicity were self-classified. The 9-item Patient Health Questionnaire (PHQ-9) was used to measure depression at baseline and quarterly intervals across 1 year, with scores of 10 or higher corresponding to moderate to severe depression.3 Participant characteristics and reported work hours the week before PHQ-9 completion were included as covariates in a logistic regression model comparing the odds of PHQ-9 scores of 10 or higher between surgical and nonsurgical interns. Inverse probability weights of being retained during follow-up were calculated and applied for all estimates and models.4 Analyses were performed using Stata, version 16 (StataCorp LLC). A 2-sided test of significance was used, with a .05 threshold.
Between 2016 and 2020 (4 annual cohorts), 12 400 interns participated in the study, 2793 of whom were surgical interns (overall response rate, 55.9%). Table 1 provides participant demographic characteristics. The baseline prevalence of depression among surgical interns was 3.4% (95% CI, 2.7%-4.3%). Among those without depression at baseline, 32.2% (95% CI, 30.3%-34.3%) exceeded the threshold of depression on 1 or more quarterly surveys, with the mean PHQ-9 score increasing by 5.4 (95% CI, 5.2-5.6) points. Female sex, nonheterosexual orientation, nonpartnered status, higher baseline neuroticism and early childhood adversity scores, and mean and maximum work hours were associated with new-onset depression.
In a multivariable, weighted regression model that included interns without baseline depression and adjusted for baseline variables listed in Table 1, surgical interns had higher odds of new-onset depression than nonsurgical interns (odds ratio [OR], 1.14; 95% CI, 1.03-1.27). However, the association reversed after controlling for maximum work hours (OR, 0.85; 95% CI, 0.75-0.96).
Persistence of depression was common, with 64.1% (95% CI, 59.8%-68.2%) of participants with new-onset depression meeting depression criteria on at least 1 additional follow-up assessment during the first year of training. Mental health care was underused, with only 26.5% (95% CI, 23.3%-30.0%) of interns with new-onset depression seeking treatment (Table 2).
In this cohort study, the baseline depression rate (3.4%) revealed that incoming surgical interns were less depressed than same-aged peers, with prevalence of depression estimated at 7.7% among the general population of 26- to 34-year-olds.5 However, the high incidence (32.2%) of new depression among surgical interns far exceeded same-aged peers (5%-10% per year6).
Several possible explanations of new-onset depression among surgical interns exist. An association between long work hours and incident depression may explain the higher rates of depression among surgical vs nonsurgical interns. In addition, sex, partner status, and sexual orientation were all associated with incident depression. Taken together, characteristics of both interns and the surgical work environment offer possible explanations for the higher-than-expected rates of incident depression.
These results revealed that depression in surgical interns is not transient and persists at least short term, with markedly higher rates throughout the year of follow-up among those with new-onset depression. We also found low receipt of mental health treatment, the reasons for which are beyond the scope of this analysis.
Limitations of this study are the short follow-up period, which limited the ability to understand whether this depression is transient or persistent, and the unique training environment of US first-year residents compared with other countries. Future analyses will consider the consequences of depression early in medical training for persistent depression after completion of training, the sequelae of depression during training for professional achievement and retention, and the ramifications of mental health for the delivery of safe and high-quality health care.
Accepted for Publication: February 6, 2022.
Published Online: April 27, 2022. doi:10.1001/jamasurg.2022.0618
Corresponding Author: Tasha M. Hughes, MD, MPH, Department of Surgery, University of Michigan Medical School, 1500 E Medical Center Dr, Ann Arbor, MI 48109 (tmhughes@med.umich.edu).
Author Contributions: Drs Hughes and Bohnert had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Hughes, Waljee, Bohnert.
Acquisition, analysis, or interpretation of data: Waljee, Fang, Sen, Bohnert.
Drafting of the manuscript: Hughes, Waljee.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Hughes, Fang, Bohnert.
Obtained funding: Sen.
Administrative, technical, or material support: Waljee.
Supervision: Hughes, Sen.
Conflict of Interest Disclosures: None reported.
Funding/Support: This study was supported in part by grant R01-MH101459 from the NIH for the development and maintenance of the Intern Health Study (Dr Sen).
Role of the Funder/Sponsor: The NIH had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.