Quality of life and treatment effectiveness direct and indirect effects on cocaine abstinence outcomes during cocaine use disorder treatment.

BACKGROUND: Patient-perceived Quality-of-Life (QOL) and treatment effectiveness (TEA) have previously been shown to be positively associated with better substance use treatment outcomes. OBJECTIVES: This study examined potentially causal relationships amongst QOL, TEA, and cocaine abstinence. METHODS: Secondary data analyses (CTN-0148) were conducted on the NIDA Clinical Trial Network study, Cocaine Use Reduction with Buprenorphine (CTN-0048). N = 301 participants with DSM-IV cocaine dependence and opioid use history were administered injectable naltrexone and randomized to one of three buprenorphine/naloxone doses, 4mg/1mg, 16mg/4mg or placebo. Mediation models estimated direct and indirect effects amongst QOL, TEA, and cocaine abstinence. RESULTS: The QOL Environment domain exerted a significant indirect effect (B=0.01, SE=0.01, 95 % CI=[0.00, 0.02]) on cocaine abstinence and a direct effect on TEA (B=0.57, SE=0.22, 95 % CI=[0.16, 1.01]). Other QOL domains and individual QOL items exerted no statistically significant direct effects on cocaine abstinence. Overall QOL exerted a significant direct effect on TEA (95 % CI=[0.32, 2.45]) along with a significant indirect effect on cocaine abstinence (95 % CI=[0.01, 0.05]). TEA had a significant positive direct effect on cocaine abstinence (95 % CI=[0.01, 0.02]). CONCLUSION: Overall QOL and environmental QOL are related to treatment response through their relationship with patients' perception of treatment effectiveness. TEA is directly related to cocaine abstinence at the end of treatment. QOL and TEA measures may serve as indicators of a need for additional support within care plans. These findings highlight the impact of a patient's sense of well-being and their perceived treatment effectiveness on biochemically validated cocaine abstinence.