The prevalence of major depression and suicidal ideation in medical residents is much higher than that of the general population. It is also higher compared to other groups of medical professionals in Europe, America, and South Asia(Becker et al.; Dyrbye et al., 2014; Lin et al., 2017; Mata et al., 2015). Depression can adversely affect the mind, body, and family, but also may affect residency work performance, subsequently leading to increased medical mistakes and adverse treatment outcomes for patients. Only one-third of patients with psychological disorders were reported to seek professional help(Crowe et al., 2016; Kohn et al., 2004; Phillips et al., 2009; Schernhammer & Colditz, 2004). Therefore, we developed and validated a nomogram to predict major depression and suicidal ideation in medical residents based on a multicenter, cross-sectional survey that included comprehensive potential predictive factors.
We found that nearly half of medical residents experienced depressive symptoms, almost one-eighth experienced major depression, and one-tenth experienced suicidal ideation. A meta-analysis from the United States and Canada estimated the prevalence of depression to be 29% among resident physicians, and this number continued to rise in each subsequent year of training(Brunsberg et al., 2019). A review showed that 6% of 18–25-year-olds in the United States have experienced suicidal ideation(Harmer, Lee, Duong, & Saadabadi, 2021). Compared with these previously published studies, we found that Chinese medical residents experienced a higher rate of major depression and suicidal ideation. We identified four shared predictive factors (sleep quality, MBI-PA, MBI-DP, and optimism of PsyCap) that affected both major depression and suicidal ideation, along with another two predictive factors (working duration and MBI-EE) that exclusively affected major depression.
Our study suggests that poor sleep quality is closely associated with both major depression and suicidal ideation. Resident physicians reported a mean sleep duration of less than 7 h, and nearly half of the study subjects slept for less than 7 h per night. Furthermore, the medical residents in our study experienced poor sleep quality or felt sleepy during the day, and one-third reported a lack of energy. A joint consensus statement of the American Sleep Association recommends a minimum sleep duration of 7 h, utilizing a modified RAND appropriateness method(Watson et al., 2015). Poor sleep quality has a negative effect on mental health, physical health, and quality of life(Giorgi, Mattei, Notarnicola, Petrucci, & Lancia, 2018). In a review of seven prospective studies that included a total of 25,271 adults, poor sleep quality was found to be significantly associated with an increased risk of depression in adults(Zhai, Zhang, & Zhang, 2015). There are several possible mechanisms through which poor sleep quality affects depression. Sleep quality is associated with abnormal cortical activation patterns, including abnormalities in the anterior frontal, medial temporal, and parietal lobes. Furthermore, reduced hippocampal growth factor levels were observed following poor sleep quality(Drummond & Brown, 2001; Kandel, 2001), thereby exerting a crucial influence on major depression and suicidal ideation, in addition to learning and memory consolidation(Curcio, Ferrara, & De Gennaro, 2006). However, a cross-sectional study of 200 community-dwelling adults in the United States found that a history of depression resulted in impaired quality of sleep(Motivala, Levin, Oxman, & Irwin, 2006). Therefore, there may be a bidirectional relationship between sleep and depressive symptoms.
A cross-sectional study of 281 adults in the United States reported that sleep disorders promoted the appearance of suicidal ideation. Insomnia was also reported to have an impact on suicidal risk(DeShong & Tucker, 2019). Additionally, a cross-sectional study of 434 suicide victims in Spain found that reduced sleep duration also promoted the development of suicidal ideation(Blasco-Fontecilla et al., 2011). Similar to previous reports, we found that sleep was a predictive factor of suicidal ideation in Chinese medical residents. This may be explained mechanistically by serotonin, which plays an important role in the induction, continuity, and formation of suicidal thoughts(Ursin, 2002).
Our study suggests that MBI-PA and MBI-DP are associated with both major depression and suicidal ideation, and that MBI-EE is associated with major depression exclusively. Burnout is a psychological syndrome that is a long-term response to chronic interpersonal stressors at work. Three key aspects of this response are a sense of PA, DP, and EE(Maslach & Leiter, 2016). A sense of PA is described as demoralization and reduced ability; DP is described as an inappropriate or negative attitude, irritability, withdrawal, and loss of idealism; and EE is described as a loss of energy accompanied by fatigue.
A longitudinal study of 2555 dentists in Finland found that burnout was an important predictor of depressive symptoms and a mediator between stress and depression(Ahola & Hakanen, 2007). A Danish repeated-measures time-to-event analysis of 2936 adults(Madsen, Lange, Borritz, & Rugulies, 2015) documented an increase in the frequency of antidepressant medication use with increasing burnout among patients. In addition, both EE and DP were independent risk factors for depressive symptoms in a longitudinal cohort study of 4287 medical students in the United States(Dyrbye et al., 2008). These conclusions are consistent with the results of our study. One potential mechanism to explain these findings is that epigenetic studies advocate for DNA methylation as a possible biomarker for stress-related mental disorders with co-expression in burnout, depression, and chronic stress(Koutsimani, Montgomery, & Georganta, 2019).
On the other hand, suicidal ideation is a severe manifestation of depressive symptoms. A longitudinal analysis of burnout in medical students in the United States concluded that DP and reduced PA were independent risk factors for suicidal ideation, and that this could not be alleviated by controlling burnout(Dyrbye et al., 2008). However, another cross-sectional study of 146 community nurses in Spain found different results; EE was reported to play an important role in the formation of suicidal ideation(Tomás-Sábado et al., 2010). The discrepancy may result from differences between subpopulations.
Optimism of PsyCap was a predictable factor for both major depression and suicidal ideation in this study. In line with our study, a cross-sectional study of 24,888 university teachers in China found that psychological capital was negatively correlated with depressive symptoms(Shen et al., 2014). Furthermore, optimism, resilience, and hope were negatively correlated with major depression in another cross-sectional survey of 2500 underground coal miners in China(Liu, Wen, Xu, & Wang, 2015). PsyCap played a mediating role for suicidal ideation and occupational stress in a stratified-cluster sampling of 2216 employees in China(Gao et al., 2020). Previous studies have suggested that optimism can affect immune function, regulating activity of natural killer cells (NKCs) and cytotoxic T-cells(Brydon, Walker, Wawrzyniak, Chart, & Steptoe, 2009). However, a prospective, repeated measurement study by Bakker(Bakker, Lyons, & Conlon, 2017) reported that self-efficacy and hope were negatively correlated with depression, while the other two elements of psychological capital had no clear relationship.
In this study, we found that medical residents were more likely to experience major depression if their work duration was greater than 60 h or less than 40 h. A cross-sectional survey of 24,922 surgeons in America demonstrated that working more than 60 h per week in a hospital was significantly negatively correlated to mental health(Shanafelt et al., 2009). Furthermore, a cross-sectional electronic survey of 976 physician trainees in the United States(Sharp et al., 2021) found that trainees completing more than 70 h of clinical work per week with heavy electronic documentation were more likely to suffer from burnout and depression. Working longer hours can lead to physical consequences (such as increased risk of stroke or coronary heart disease) and mental health problems, and the stress and subjective experience of disease plays an important role in mental disorders(Choi et al., 2021). Meanwhile, another cross-sectional study of 753 general surgery trainees in the United States(Elmore, Jeffe, Jin, Awad, & Turnbull, 2016) reported that shorter working hours and reduced receipt of superior physician teaching hours resulted in a lower sense of personal accomplishment, and even led to major depression. Therefore, appropriate work intensity and opportunity to learn more are beneficial for reducing the risk of depression.
This study is not without limitations. First, this is a multicenter cross-sectional study and cannot assess causal relationships between variables. Therefore, longitudinal studies are needed to validate our conclusions. Second, the use of self-reporting questionnaires may lead to recall or reporting bias. Third, the PHQ-9 questionnaire was used to screen for depression, not to provide clinical diagnoses, and this may affect the true prevalence of depression. The confirmatory scale for diagnosing depression is too complex to assess using a survey, and psychological professionals are required to do so. Fourth, unmeasured confounders like genetic variants may have an impact on major depression and suicidal ideation. Fifth, the recruited participants were confined to northeastern China and additional subjects remain to be validated in other regions of China. Despite these limitations, this is the first nomogram for predicting major depression and suicidal ideation in Chinese medical residents based on a multi-center study with excellent external validation. In addition, we evaluated a large number of potentially predictive factors among psychological characteristics, work-related factors, and life-related factors, while excluding confounders.