Association of COVID-19 Pandemic with Newly Diagnosed Anorexia Nervosa among Children and Adolescents in Japan

Background: Research from Western countries shows an increased trend of Anorexia Nervosa (AN) among children and adolescents after the COVID-19 pandemic. However, the trend in other countries remains unclear. This study aimed to examine the association of the COVID-19 pan-demic with newly diagnosed AN among children and adolescents in Japan. Methods: Using the nationwide multi-hospital database in Japan, we analyzed the clinical outpatient data in the de-partments of pediatrics, psychosomatic medicine, and psychiatry. The participants comprised children and adolescents aged 7-19 years newly diagnosed with AN from January 2017 to January 2022. An interrupted time series analysis was conducted to compare the trends of newly diag-nosed AN before and after the COVID-19 pandemic. Estimating the changes in the trends over the pandemic was done using a Poisson regression model. Results: The total cases of newly di-agnosed AN was 41 (1.08 cases per month) before the pandemic and 34 (1.48 cases per month) af-ter the pandemic. Notably, in the 7-14 age group, the cases per month increased from 0.74 to 1.13 cases per month over the period. Before the pandemic, a noticeable decrease in cases was ob-served (Incidence Rate Ratio [IRR]= 0.961; 95% CI= 0.932–0.990). Conversely, the after-pandemic period showed a contrasting trend, with an increase in cases (IRR= 1.096; 95% CI= 1.032- 1.176). Conclusions: The COVID-19 pandemic was associated with the increase in newly diagnosed AN among children and adolescents in Japan as well as Western countries. The development of AN after the pandemic might be more affected by individual, parental, and peer factors than soci-ocultural factors.