The changing gender gap in substance use disorder: a total population-based study of psychiatric in-patients

Aims: To study changes over a 25-year period in the gender gap in discharge diagnoses of alcohol use disorder (AUD) and other substance use disorder (SUD) in psychiatric in-patients.

Design, setting and participants: A register-based study of all admissions to psychiatric hospitals in Iceland between January 1983 and December 2007.

Measurements: Annual rate of admissions to psychiatric hospitals, adjusted for changes in the size of the population. Furthermore, gender-specific analysis of changes in discharge diagnoses of AUD solely and other SUD (including AUD with other SUDs).

Findings: Of all psychiatric admissions, the proportion of any SUD admissions increased considerably during the study period. This increase was most pronounced in SUDs other than solely AUD. AUD increased for women and decreased for men. The male to female ratio of AUD alone decreased from 4.2 to 1.5 (P < 0.001). There was no significant change in the gender gap for other SUDs (P = 0.96).

Conclusions: There has been a marked convergence of the gender gap in discharge diagnosis of alcohol use disorder among psychiatric in-patients in Iceland over the last decades. For other substance use disorders, the change was not as pronounced. Our results emphasize the importance of monitoring changes in substance use disorder diagnosis as this may uncover different treatment needs in this group of vulnerable individuals.