BACKGROUND: During previous pandemics people who use drugs (PWUD) were categorized among the most vulnerable. In the current study, firstly, we wanted to evaluate the impact of the COVID-19 crisis on the prevalence of anxiety and depressive disorders among PWUD. Furthermore, we wanted to compare the prevalence of these disorders with that of members from the general population who did not use drugs.

METHODS: We used a matched cohort design based on two separate repeated cross-sectional online surveys (April and November 2020) among PWUD and the general population. Results of GAD-7 and PHQ-9 were used as outcome variables. We calculated absolute and relative risks for matched pairs for both affective disorders, and logistic regression to compare affective disorders over both waves for PWUD.

RESULTS: In April, the prevalence of affective disorders was similar for PWUD and the general population. In November, the risks for anxiety disorders increased with 64% for PWUD compared to non-PWUD (RR = 1.64, 95%CI 1.42-1.88), whereas the risks for depressive disorders more than doubled (RR = 2.29, 95%CI 1.97-2.67). Having a job and being male were protective factors for PWUD for both anxiety and depressive disorders.

LIMITATIONS: As this study used self-reported data, GAD-7 and PHQ-9 give an indication of the presence of anxiety and depression which might differ from a clinician's judgement.

CONCLUSIONS: PWUD might be disproportionally affected by COVID-19. Health care providers should be attentive to substance use as an indicator for increased risk of mental health problems.