Long-term Age- and Region-Specific Changes in Psychiatric Service Utilization Following Japan's First COVID-19 State...

To evaluate nationwide long-term changes in psychiatric service utilization across age groups following Japan's first COVID-19 state of emergency and to compare these changes across regions with different states of emergency intensities.

This population-based interrupted time-series study used publicly available aggregated data derived from the National Database of Health Insurance Claims from April 2013 to April 2024, covering nearly all psychiatric patients in Japan. Segmented regression was used to estimate changes after the first state of emergency (April-May 2020). Outcomes were mean daily numbers of psychiatric outpatient visits and inpatient care per 100,000 population. Prefectures were categorized as high-, middle-, and low-intensity regions by the cumulative duration of subsequent declarations.

Slope changes in psychiatric outpatient visits varied substantially by age and region. Pre-existing upward trends accelerated after the state of emergency among patients aged 15-39 and 60-69 years, with greater acceleration in high-intensity regions than in middle- or low-intensity regions. The largest change was observed among patients aged 20-24 years in high-intensity regions (0.54 [95% CI, 0.46-0.63]), compared with middle-intensity (0.34 [95% CI, 0.27-0.41]) and low-intensity regions (0.42 [95% CI, 0.34-0.50]). In contrast, psychiatric inpatient care generally declined across most age groups and regions.

Following the first state of emergency, psychiatric outpatient visits increased with marked heterogeneity by age group and region, with more pronounced acceleration in high-intensity regions. These findings underscore the value of age- and region-specific monitoring of psychiatric service utilization during future public health crises.