Methylphenidate abuse and knowledge about its risk among patients in methadone maintenance treatment

Background: Methylphenidate is highly abused by methadone maintenance treatment (MMT) patients. However it is not routinely tested by the national authority. Predictors for methylphenidate abuse are needed. Methods: Patients filled out a questionnaire concerning methylphenidate effects, indications, and risks both before and after an explanation session. Self-reported misuse was determined with two cross-sectional evaluations and sporadic random screenings between 2013 and 2017. Results: Of the 237 participants, 87(36.7%) self-reported methylphenidate lifetime usage (“Ever”), while 150 reported never using it (“Never”). Forty-five (19.0%) participants tested positive for methylphenidate (36[41.4%] “Ever” vs. 9[6%] “Never”, p<0.0005). Knowledge score (ranged 0-19) was higher among the “Ever” participants when compared to the “Never” participants, and improved following the explanatory session. Logistic regression found that participants in the “Ever” group were more likely to be alone OR=2.2(95% CI 1.2-4.3) and abusing benzodiazepines after one year in MMT OR=4.6(95% CI 2.5-8.3). Furthermore they also had a higher pre-session knowledge score OR=1.1 (95% CI 1-1.2). A high score also characterized 9 “Never” patients whose urine was positive for methylphenidate. Conclusion: A high knowledge score may reflect methylphenidate abuse, independent of self-reported information. Self-reporters of methylphenidate usage were also found to abuse benzodiazepines.