Variability in outcomes and quality-of-care indicators across clinics participating in a large smoking-cessation program

Background: The effectiveness of care for substance-related problems varies across providers. Best-known treatments are rarely universally applied, and various process differences can affect participant outcomes. Measuring and understanding this variability can suggest changes that will improve system performance. Methods: We measure variability in 7-day cigarette abstinence at a six-month follow-up; return for a second clinical visit; and receipt of combination nicotine replacement therapy across 223 primary care clinics participating in the Smoking Treatment for Ontario Patients program, a large smoking cessation initiative in Ontario, Canada. We include 41,992 enrolments from April 11, 2016 and May 31, 2019. We risk adjust for demographic and clinical case-mix differences and characterize variability using funnel plots and measures based on cliniclevel variance explained. The abstinence outcome is missing for 38% of participants. We adjust for missingness using multiple imputation and inverse probability weighting. Results: Abstinence was achieved by 28.0% (95% CI = 27.5%-28.5%) of participants, 63.2% (62.8%-63.7%) received combination NRT, and 72.9% (72.4%-73.3%) returned for a second clinical visit. Variability was moderate for abstinence (median odds ratio (MOR) = 1.16) and pronounced for return visit (MOR = 1.29) and combination therapy (MOR = 1.89). Conclusion: Outcomes and processes vary significantly across clinics within a program with shared guidelines and standards. Differences across providers may be greater in other contexts. Results underscore the importance of measuring and understanding variability, and of ongoing maintenance and improvement. The existence of high outliers holds out the possibility of identifying practices that might be more widely adopted.