Obsessive-compulsive symptom scores during three months of opioid maintenance treatment: a prospective observational cohort study

Y-BOCS-rated obsessive-compulsive phenomena during opioid use disorder treatment may overlap with craving, withdrawal-related distress, and drug-related preoccupation and should not be assumed to represent primary obsessive-compulsive disorder (OCD). Longitudinal comparative data are limited, particularly for opium tincture in Iran. In a single-center prospective observational cohort, adults initiating methadone, buprenorphine, or opium tincture completed the Persian-language Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at baseline and three months with the same unblinded psychologist. Y-BOCS was treated as a severity measure, not a diagnostic instrument; only total scores were available. We used Wilcoxon signed-rank tests for within-group change, Kruskal-Wallis with Holm-adjusted Mann-Whitney tests for raw between-group change, and an HC3-robust baseline-by-treatment model, with age-sex adjustment as sensitivity analysis. The cohort included 272 participants: methadone n = 95, opium tincture n = 90, and buprenorphine n = 87. Mean Y-BOCS decreased from 17.03 (SD = 6.67) to 13.04 (SD = 5.79), a mean reduction of 3.99 points (95% CI [3.63, 4.34]); all within-group tests had p < .001. Mean reductions were 3.24, 3.43, and 5.37 points, respectively. Raw change differed across groups (H(2) = 34.73, p < .001); methadone and opium tincture did not differ (Holm-adjusted p = .579), while buprenorphine showed larger raw reductions than both comparators (both p < .001). Baseline Y-BOCS was higher with buprenorphine (20.93 vs. 15.09 and 15.29), and the baseline-by-treatment interaction was significant (F(2, 266) = 6.58, p = .002). At baseline Y-BOCS = 20, the adjusted buprenorphine-versus-methadone contrast was not significant ( p = .080). The interaction remained significant after age-sex adjustment (F(2, 258) = 6.55, p = .002). Y-BOCS scores decreased during three months of opioid maintenance treatment, but this does not establish improvement in primary OCD and may partly reflect stabilization of withdrawal-related distress or opioid-related preoccupation. The larger raw buprenorphine reduction should not be interpreted as superiority because baseline scores were higher, treatment assignment was nonrandom, and differences depended on baseline severity. Future studies should characterize symptom content and directly measure craving, withdrawal, anxiety, and other psychiatric symptoms. Not applicable. Treatment was selected as part of routine clinical care and was not assigned by the investigators.