Risk of self-harm in first-diagnosed mental disorders: A 16-year territory-wide health-record database study in Hong Kong.

Mental disorders (MDs) are established risk factors for self-harm, yet disorder-, age-, and sex-specific risk estimates in population-representative samples are rarely studied. We conducted a territory-wide, population-based cohort study using Hong-Kong medical record database covering public hospitals, specialist and general outpatient clinics, identifying 322,922 people with a first-recorded diagnosis of any MDs and 888,031 primary-care controls without MDs (proxy general population) between 1-January-2006 and 31-December-2021. Outcomes were incident self-harm events. Cox proportional-hazards models estimated hazard ratios (HRs) adjusting for sex, age-group, physical-comorbidity, and calendar-year; incidence rates (IRs) and HRs by each diagnostic-group, age-group and sex were generated. Over 3031,600.9 person-years, the MD cohort had an IR of 60.2 per 1000 person-years (95%CI 59.5-61.0), with HR 10.59(10.31-10.89). Elevated self-harm risk was observed across all fourteen diagnostic-groups, highest for substance use disorders (SUD, 22.86[21.47-24.34]), followed by alcohol use disorders (AUD,14.59[13.49-15.79]), personality disorders (PD,7.81[5.60-10.89]), major depressive disorder (7.48[7.14-7.85]), eating disorders (6.56[4.07-10.58]), bipolar disorder (6.43[5.71-7.24]), attention deficit/hyperactivity disorder (ADHD,6.09[5.51-6.73]), schizophrenia (5.00[4.63-5.40]), autism-spectrum disorders (ASD, 4.88[4.35-5.48]), post-traumatic stress disorders (PTSD, 3.64[2.83-4.68]), dysthymia (3.43[3.12-3.78]), obsessive compulsive disorder (3.74[3.27-4.27]), anxiety disorders (2.26[2.09-2.44]), and organic mental disorders (2.01[1.84-2.19]). Further analyses identified substantially elevated risk of SUD (with their high standalone and compounding risk). Subgroup analyses showed the highest self-harm risks in youths (≤24 years), and female predominance across most MDs, notably in PTSD, PD, AUD, ASD and ADHD. Taken together, this territory-wide electronic-health-record study maps the transdiagnostic nature of self-harm across first-diagnosed MDs, and further research to confirm the special vigilance for the at-risk subgroups/diagnostic groups.