The aim of the study is to investigate clinically meaningful, secondary outcomes in a randomized trial of a culturally adapted contingency management (CM) intervention for alcohol use in 3 diverse American Indian and Alaska Native communities.
Three American Indian and Alaska Native communities located in the Northern Plains, Alaska, and the Inland Northwest were partnering sites. A total of 158 individuals were randomized to either a 12-week CM intervention or a noncontingent (NC) control group. The CM group received reinforcers for providing alcohol-negative ethyl glucuronide (EtG < 150 ng/mL) urine samples, while the NC group received reinforcers unconditionally. Outcomes included EtG as a continuous measure (range, 0–2,000 ng/mL), EtG > 499 ng/mL (a measure of higher levels of recent alcohol use), longest duration of abstinence, and time-to-first alcohol-positive EtG during the trial. Generalized estimating equations along with Cox proportional hazard and negative binomial regressions were used.
Participants randomized to the CM group had lower mean EtG levels (−241.9 ng/mL; 95% confidence interval [CI], −379.0 to −104.8 ng/mL) and 45.7% lower odds (95% CI, 0.31 to 0.95) of providing an EtG sample indicating higher levels of alcohol use during the intervention. Longest duration of abstinence was 43% longer for the CM group than the NC group (95% CI, 1.0 to 1.9). Risk of time-to-first drink during treatment did not differ significantly.
These secondary outcome analyses provide evidence that CM is associated with reductions in alcohol use and longer durations of abstinence (as assessed by EtG), both clinically meaningful endpoints and analyses that differ from the primary study outcome.