Constant 2021.

Study characteristics
Methods	Study design: randomized controlled trial Country: Brazil Setting: telephone counseling call center Eligibility criteria: adults who self‐reported alcohol use and the desire to stop drinking Duration of follow‐up: 6 months Informed consent: participants provided informed consent Ethical approvals: study procedures were approved by the Committee of Research Ethics at the Federal University of Healthcare Sciences of Porto Alegre ‐ UFCSPA.
Participants	Sample size: 1400 (687 ntervention, 713 control) Description of the target population: adults seeking support from a call center to stop drinking Age: 32.9 years (SD = 10.3) Sex: 78% male Race/Ethnicity: not reported Marital status: not reported Harmful alcohol use (baseline): 88% met DSM‐5 criteria for alcohol use disorder Co‐occurring disorders: 11% of participants reported only alcohol consumption, 10.4% reported combined alcohol and cocaine use, 11% reported combined alcohol and tobacco use, 67.6% reported combined alcohol with other illegal drug use
Interventions	Type: non‐pharmacologic Description: brief motivational intervention including information and counseling on alcohol and drugs by phone Duration and frequency: 7 telephone contacts (40 minutes each) Delivery and provider: telephone counselors who received training and supervision Comparison group:iInformation and counseling on drugs by phone (7 telephone contacts, 40 minutes each)
Outcomes	Primary outcome(s): alcohol consumption Primary outcome measurement tool(s): not reported Secondary outcome(s): Motivation to change behavior; Coping Secondary outcome measurement tool(s): Contemplation ladder; Coping Behaviors Inventory Time points: 1, 2, and 7 days; 1, 2, 3, and 6 months
Notes	Study funding and conflicts of interest: not reported Linked study records: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The inclusion in each group followed random sampling using a random number technique (Microsoft software application)." Pg. 2
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of providers and participants not possible given the nature of the intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	High rates of attrition (>50%)
Selective reporting (reporting bias)	Unclear risk	Not reported