Evaluating the Impact of Urine Drug Screen Frequency on Retention in Opioid Agonist Treatment in Ontario, Canada

Abstract ObjectiveThe objective of this study was to evaluate how UDS frequency impacts treatment retention in OAT. MethodsData for this retrospective cohort study of 55,921 adults with OUD in Ontario, Canada, were derived from administrative data sources between January 1, 2011, and December 31, 2015. All patient information was linked anonymously across databases using encrypted ten-digit health card numbers. Descriptive statistics were calculated for comparing urine drug screening frequency groups (less than monthly, monthly, bi-weekly and, weekly) using standardized differences (d) where d less than 10% indicated a statistically significant difference. A logistic regression model was then used to calculate odds ratios for the association between UDS frequency and one-year treatment retention adjusting for baseline covariates, including sex, age, location of residence, income quintile, mental disorders, HIV status and deep tissue infections. ResultsOver 70 percent of the cohort had four or more UDS per month (weekly or more UDS). Significant associations were observed between UDS frequency and one-year treatment retention in OAT bi-weekly (adjusted Odds Ratio (aOR) = 3.20, 95% confidence interval (CI) 2.75-3.75); weekly UDS (aOR = 6.86, 95% CI, 5.88-8.00) and; more than weekly (aOR = 8.03, 95% CI, 6.87-9.38) using the monthly or less groups as the reference.ConclusionThis study identified a significant association between weekly UDS and one-year treatment retention in OAT. Therefore, these findings put into question the recent changes in OAT guidelines recommending UDS only be conducted monthly. More research is needed to strengthen the evidence base for UDS frequency in OAT.