Variables associated with methamphetamine use within the past year and sex differences among patients with methamphetamine use disorder: A cross-sectional study in Japan.

BACKGROUND AND OBJECTIVES: Methamphetamine use disorder is the most common reason for psychiatrist visits among illicit drug users in Japan. Although variables associated with methamphetamine use and sex differences have been reported in the United States, Australia, and Asian countries, such studies are rare in Japan. We examined methamphetamine use within the past year among patients receiving treatment by sex and proposed important treatment targets. METHODS: This cross-sectional study analyzed the Nationwide Mental Hospital Survey on Drug-related Psychiatric Disorders. We divided 1086 men and 376 women into two groups according to methamphetamine use within the past year and conducted log-binomial regression analyses by sex to examine the variables associated with methamphetamine use. For methamphetamine users, the source was identified. RESULTS: Women were more likely to obtain methamphetamine from their friends, acquaintances, family members, or partners than men. Multivariable regression analysis showed that younger age in both sexes and higher educational attainment (prevalence ratio [PR] = 1.29; 95% confidence interval [CI] = 1.06-1.57) and employment (PR = 1.26; 95% CI = 1.05-1.51) were associated with methamphetamine use in men. Age-adjusted regression analysis showed that the variables associated with methamphetamine use were comorbid alcohol abuse and cannabis abuse in women and benzodiazepine abuse in both sexes. CONCLUSION AND SCIENTIFIC SIGNIFICANCE: In women, in particular, the surrounding relationships related to methamphetamine might be considered treatment targets. Young and working patients might need more accessible outpatient clinics and treatment programs. Comorbid substance abuse should be assessed and treated.