Duration of New-Onset Depressive Symptoms During Medical Residency

The implications of new-onset depressive symptoms during residency, particularly for first-year physicians (ie, interns), on the long-term mental health of physicians are unknown.

To examine the association between and persistence of new-onset and long-term depressive symptoms among interns.

The ongoing Intern Health Study (IHS) is a prospective annual cohort study that assesses the mental health of incoming US-based resident physicians. The IHS began in 2007, and a total of 105 residency programs have been represented in this national study. Interns enrolled sequentially in annual cohorts and completed follow-up surveys to screen for depression using the 9-item Patient Health Questionnaire-9 (PHQ-9) throughout and after medical training. The data were analyzed from May 2023 to March 2024.

A positive screening result for depression, defined as an elevated PHQ-9 score of 10 or greater (indicating moderate to severe depression) at 1 or more time points during the first postgraduate year of medical training (ie, the intern year).

The main outcomes assessed were mean PHQ-9 scores (continuous) and proportions of physicians with an elevated PHQ-9 score (≥10; categorical or binary) at the time of the annual follow-up survey. To account for repeated measures over time, a linear mixed model was used to analyze mean PHQ-9 scores and a generalized estimating equation (GEE) was used to analyze the binary indicator for a PHQ-9 score of 10 or greater.

This study included 858 physicians with a PHQ-9 score of less than 10 before the start of their internship. Their mean (SD) age was 27.4 (9.0) years, and more than half (53.0% [95% CI, 48.5%-57.5%]) were women. Over the follow-up period, mean PHQ-9 scores did not return to the baseline level assessed before the start of the internship in either group (those with a positive depression screen as interns and those without). Among interns who screened positive for depression (PHQ-9 score ≥10) during their internship, mean PHQ-9 scores were significantly higher at both 5 years (4.7 [95% CI, 4.4-5.0] vs 2.8 [95% CI, 2.5-3.0]; P < .001) and 10 years (5.1 [95% CI, 4.5-5.7] vs 3.5 [95% CI, 3.0-4.0]; P < .001) of follow-up. Furthermore, interns with an elevated PHQ-9 score (≥10) demonstrated a higher likelihood of meeting this threshold during each year of follow-up.

In this cohort study of IHS participants, a positive depression screening result during the intern year had long-term implications for physicians, including having persistently higher mean PHQ-9 scores and a higher likelihood of meeting this threshold again. These findings underscore the pressing need to address the mental health of physicians who experience depressive symptoms during their training and to emphasize the importance of interventions to sustain the health of physicians throughout their careers.