Table 1 PICO and PICo criteria for review questions Q1 and Q2

Q1: What was the impact of relaxing restrictions on take-home doses during the COVID-19 pandemic on program effectiveness in OAT, as indicated by (1) retention; (2) illicit substance use; (3) fatal and non-fatal overdose; (4) client health; (5) quality of life; and (6) treatment satisfaction?

P (Population): People receiving OAT via any route of administration (e.g., oral, sublingual, buccal, injectable)

I (Intervention): Relaxation of restrictions on take-home doses of OAT during the COVID-19 pandemic^a

C (Comparator): (1) No comparator OR (2) restrictions on take-home doses prior to the COVID-19 pandemic

O (Outcomes): Program effectiveness, as indicated by incidence of (1) retention; (2) illicit substance use; (3) fatal and non-fatal overdose; (4) client health; (5) client quality of life; and (6) client treatment satisfaction

Q2: What was the impact of relaxing restrictions on take-home doses during the COVID-19 pandemic on clients’ experiences with OAT?

P (population): People receiving OAT via any route of administration (e.g., oral, sublingual, buccal, injectable)

I (phenomenon of Interest): Client experience (e.g. satisfaction with treatment, relationship with provider, self-efficacy, alignment of service with personal treatment goals, other patient-reported outcomes)

Co (Context): Relaxation of restrictions on take-home doses of OAT during the COVID-19 pandemic^a