Biennial Changes in the Characteristics of Patients with Methamphetamine Use Disorder in Japan from 2000 to 2020.

Methamphetamine is an illegal drug with the greatest burdens in Japan. Social and medical measures to combat methamphetamine dependence have been implemented, but no reports on changes in the characteristics of methamphetamine use disorder patients have been conducted. We aimed to describe these changes, and provide information on the results of social and medical measures. We concatenated cross-sectional surveys from 2000 to 2020 and analyzed biennial changes. Twenty-year data from 2000 to 2018 were age-weighted according to the age structure in 2020. We performed Cochran-Armitage trend tests for crude and age-weighted changes in patient variables. There was an increase in the number of patients with methamphetamine use disorder undergoing treatment and those with a history of drug-related arrests. Patients who achieved 1-year abstinence increased, and those diagnosed with psychotic disorders decreased. Patients with a history of non-drug-related arrests and without revealing their source of methamphetamine decreased. The ages of the patient population increased, and patients with a history of benzodiazepine misuse increased. Social measures linking methamphetamine users to psychiatric care may increase the number of patients who undergo treatment.