Impact of community mental health services on the adult psychiatric admission through the emergency unit: a 20-year population-based study.

Background: There is a lack of real-life population-based study examining the effect of community mental health services on psychiatric emergency admission. In Hong Kong, Integrated Community Center for Mental Wellness (ICCMW) and telecare service were introduced in 2009 and 2012, respectively. We examined the real-life impact of these services on psychiatric emergency admissions over 20 years. Methods: Number of psychiatric emergency admissions between 2001 and 2020 was retrieved from the Hong Kong Clinical Data Analysis & Reporting System. We used an interrupted time series analysis to examine monthly psychiatric admission trend before and after service implementation, considering socioeconomic and environmental covariates. Findings: A total of 108,492 psychiatric emergency admissions (47.8% males; 64.9% aged 18-44 years) were identified from the study period, of which 56,858, 12,506, 12,295, 11,791, and 15,051 were that for schizophrenia-spectrum disorders, bipolar affective disorders, unipolar mood disorders, neuroses, and substance use disorders. ICCMW introduction has an immediate effect on psychiatric emergency admission (adjusted estimate per 100,000: -10.576; 95% CI, -16.635 to -4.518, p < 0.001), particularly among adults aged 18-44 years (-8.543; 95% CI, -13.209 to -3.877, p < 0.001), females (-5.843; 95% CI, -9.647 to -2.039, p = 0.003), and with neuroses (-3.373; 95% CI, -5.187 to -1.560, p < 0.001), without a significant long-term effect. Unemployment, seasonality, and infectious disease outbreak were significant covariates. Interpretation: ICCMW reduced psychiatric emergency admission, but no further reduction following full implementation. Community mental health services should be dynamically tailored for different populations and socioeconomic variations over time. Funding: None.