Elevated depressive symptoms among newer and younger healthcare workers in Japan during the COVID‐19 pandemic

Abstract Aim Depression is a frequent outcome of long‐term stress, but no studies have examined depression rates among Japanese healthcare workers fighting the COVID‐19 pandemic. Therefore, we conducted a web‐based interview of hospital employees to assess depression prevalence and factors. Methods This observational cohort study was conducted from July to August, 2020, as part of a mandatory health checkup of Juntendo University Hospital employees (Tokyo, Japan). A total of 4239 participants completed a web‐based questionnaire on medical history and current health status. The Center for Epidemiologic Studies Depression Scale (CES‐D) was used for self‐assessment, with a score of ≥16 considered to indicate depression. Results Among all employees, the proportion of depression was 31.3% in 2020, the highest measured in the last 10 years and substantially greater than the pre‐pandemic value in 2019 (27.5%). The proportion of depression for 2020 was significantly higher in new recruits than in employees with more than 2 years of experience (47.0% vs 29.9%, respectively, P < .0001) and in new recruits in 2019 (26.4%, P < .0001). When subdivided by occupation, nurses demonstrated the highest depression rate (43.2%), followed by paramedics (35.1%) and clerks (31.6%), whereas residents (22.9%), doctors (20.4%), teaching staff (18.0%), and part‐time staff (15.3%) reported lower depression rates. The positive CES‐D score significantly correlated with age (P < .0001). Conclusions Younger and newer employees demonstrated the highest rates of depression independent of occupation. Therefore, mental healthcare programs focusing on these vulnerable groups need to be established.


| INTRODUC TI ON
In winter 2019, a new viral pneumonia was detected in Wuhan, Hubei Province, China, and the causative pathogen identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Within several months, the associated disease, COVID-19, had spread throughout the globe. By the end of October, 2020, the total number of infected cases exceeded 100 000 in Japan, with more than 1700 deaths. The mental health of healthcare workers involved in COVID-19 treatment is a critical factor for sustaining the global fight against this disease.
Several reports examining healthcare workers during SARS, MERS, and COVID-19 pandemics have found substantial impacts on physical and mental health, including increased susceptibility to insomnia. [1][2][3] Healthcare workers around the world have experienced significant psychological stress and will require care to continue to protect people from COVID-19. 4 The impact of the COVID-19 pandemic has recently become clear in terms of impairing psychological health and exacerbating the risk of suicide because many problems of COVID-19 are protracted. In Japan, from July 2020 to October 2020, the monthly suicide rate increased by 16%, which further increased among women, children, and adolescents. 5 The mental health of the entire population was adversely affected; however, the mental health problems of healthcare workers were even more serious. Psychological distress was reported to significantly increase in healthcare workers, in addition to fear and anxiety regarding COVID-19. 6 According to a July 2020 report, the prevalence of depressive symptoms in Japan was two to nine times higher than that before the COVID-19 pandemic. 7 Depression is a frequent outcome of long-term stress, but no studies have examined depression rates among Japanese healthcare workers fighting the COVID-19 pandemic. Therefore, we conducted a web-based interview of hospital employees to assess depression prevalence and factors associated with greater depression risk.

| ME THODS
This observational cohort study was conducted from July to August, 2020, as part of a mandatory health checkup of Juntendo University Hospital employees (Tokyo, Japan). All 4,290 employees were enrolled. The healthcare staff who were assessed included doctors, residents, nurses, paramedics, support staff, clerk, teaching staff, researchers, and part-time staff. Two study subjects who opted were thus excluded. A total of 4239 participants completed a webbased questionnaire on medical history and current health status, and the valid response rate obtained was 98.8%. The Center for Epidemiologic Studies Depression Scale (CES-D) was used for selfassessment, with a score of ≥16 considered to indicate depression.
The study protocol was approved by the Ethics Committee of the Juntendo University Faculty of Medicine (approval no. 22004).
Informed consent was obtained from all participants.
Statistical analyses were performed using SPSS ver. 22 (IBM Corp.). The chi-square test was used to assess differences in the frequencies of patient characteristics (eg, sex). Clinical variables were compared using the two-tailed Mann-Whitney U test in cases with two groups or the Kruskal-Wallis test in cases with three or more groups. A two-tailed P < .05 was considered significant for all tests.
The correlation between the participants' variables was analyzed by univariate analysis. The analysis was performed using only the variables associated with the CES-D scores. Logarithmic conversion was performed for age. The models included multiple co-variates such as gender, age, observation year, and healthcare occupation.
Observation year and healthcare occupation were tested in separate models including interaction terms of all the above-mentioned co-variates. The type used in the models was "nurse vs. non-nurse." Logistic regression analysis was performed subsequently using multiple categories as outcome variables (ie, CES-D-positive findings) to identify correlations between different clinical factors and depression.

F I G U R E 1 Changes in depression prevalence among employees of Juntendo
University Hospital and Juntendo University Graduate School of Medicine according to age group over the past decade. Depression was evaluated by the Center for Epidemiologic Studies Depression Scale (CES-D). A score of ≥16 was considered positive for depression. Depression has remained highest in the youngest age group (20s, blue), with greatest prevalence during the COVID-19 pandemic year of 2020

| RE SULTS
The prevalence of depression among all employees was 31.3% in 2020, the highest measured in the last 10 years and substantially greater than the pre-pandemic value in 2019 of 27.5%. The proportion of depression for 2020 was significantly higher in new recruits than in employees with more than 2 years of experience (47.0% vs 29.9%, respectively, P < .0001) and in new recruits in 2019 (26.4%, P < .0001). Depression was the highest in the 20s age group  (Table 1).
Center for Epidemiologic Studies Depression Scale significantly and positively correlated with age (P < .0001) and sex (P < .0001).
In addition, occupation was associated with score changes between 2019 and 2020 (P < .0001). The results from binary logistic regression analysis for the score changes between 2019 and 2020 showed that being female [odds ratio (    Average score by occupation

RE VIE WER BOARD
The study protocol was approved by the Ethics Committee of the Juntendo University Faculty of Medicine (Approval no. 22004).

ACK N OWLED G M ENTS
This study was funded by the Juntendo Mental Health Institute (2020-003). The authors thank Enago (www.enago.jp) for carefully proofreading the manuscript for language.

CO N FLI C T O F I NTE R E S T
The authors declare no conflicts of interest.

AUTH O R CO NTR I B UTI O N
All authors contributed to the conceptualization, design, and writing of this manuscript.

I N FO R M ED CO N S ENT
Informed consent was obtained from all participants.

DATA AVA I L A B I L I T Y S TAT E M E N T
Research data are not shared. The raw data belonged to the present study cannot be made publicly available because the disclosure of personal data was not included in the research protocol of the present study. The data are not publicly available due to privacy and ethical restrictions.