Abstract:
Coping self-efficacy, defined as confidence in one’s ability to abstain from drug
use in difficult situations, has been found to be a predictor of treatment outcome for
substance addiction. Cocaine addiction has received less research attention compared to
alcohol, nicotine, and opiates. The present study examined archival data from a voucher
reinforcement study where 78 opiate- and cocaine-dependent participants were
randomized to (1) a control group that received methadone maintenance, (2) a group that
earned take-home methadone doses based on abstinence, or (3) a group that earned take-home
doses as well as monetary vouchers based on abstinence. The purpose of the
present study was to determine if pre-treatment self-efficacy ratings, measured by the
Situational Confidence Questionnaire (SCQ), predicted cocaine abstinence outcomes,
measured by cocaine-negative urine samples, across 52 weeks of treatment and during
the last 13 weeks of treatment. This study also examined whether SCQ scores predicted
the period of 100% abstinence that some participants were able to sustain for over 6
months during treatment. Results of the study were mixed dependent upon how missing
urinalysis data were treated. When all missing urine samples were considered positive,
self-efficacy was not a significant predictor of future abstinence. When analyses were
performed without including missing urinalysis data, self-efficacy was predictive of
abstinence in the last 13-week block of the treatment period. A third treatment of missing
data was applied by filling in all missing urine samples with either a positive or negative
value based on the participant’s immediate prior and subsequent levels of abstinence.
This method also found that self-efficacy was a significant predictor of abstinence in the
last 13-week block of treatment. Both prior abstinence and contingent reinforcement of
abstinence were robust predictors of future abstinence, and self-efficacy was significantly
related to current drug use. The predictive ability of self-efficacy at various times in the
addiction cycle was discussed.
