Recent trend of incidence rates of hospital-treated self-harm by males in Hong Kong

Abstract

BACKGROUND: Self-harm is expected to be 10 to 20 times more frequent than suicide. Traditionally, it has been more common among females than males, but some recent studies showed similar rates across genders and even higher rates among males. In Hong Kong, 12-month prevalence rate of suicide attempts also revealed no gender difference among adolescents. AIM: To investigate the trend of gender-specific incidence rates of self-harm presenting to public hospitals in Hong Kong METHOD: 32,308 records of emergency presentation and 36,411 records of inpatient admission as a result of self-harm between 2002 and 2011 were obtained. 9,246 overlapping records were identified, resulting in 59,473 distinct episodes of self-harm by 48,460 patients. Capture-recapture approach was employed to estimate the number of undercount in the two data sources. Multinomial logit model was carried out to model the heterogeneous capture probabilities by including gender, age, method of self-harm and year of incidence as covariates. Annual incidence rates of self-harm were then calculated based on these estimated number of episodes after incompleteness adjustment. RESULTS: The average annual incidence rate of self-harm was 116.0 (95% C.I. = 115.2-116.9) per 100,000 in Hong Kong for the period 2002-2011.Incidence rate of males (121.1 per 100,000) was a little bit higher than that for females (111.5 per 100,000). The usual gender pattern sharply reversed in 2003, since when the annual rates for men have remained persistently higher than for women. This gender gap gradually widened since 2007, and self-harm by males has become 16-21% more frequent than among females in later years. Breakdown by method of self-harm suggested that the changing gender pattern was attributed to self-poisoning. Self-poisoning among females was fairly stable across the study period, but that among males experienced extraordinary increase in each of the years 2003 and 2007. Further breakdown by age group revealed that such increase could mainly be observed from working-age males. CONCLUSION: The traditional gender pattern of self-harm might have changed in Hong Kong during the past decade. Such transformation was primarily accounted for by the increased popularity of self-poisoning among men. The elevated rate of self-poisoning in 2003 and 2007 remained high afterwards and did not return to its original level. This suggests the emergence of a new cohort of male self-harming patients, and/or probably a change in their help-seeking behavior.