Another reason was that patients had health problems and needed to stop using methadone so as to have examination and 19 treatment, at 16%, and inability to pay for methadone treatment was also a reason with 14.8%. The result of multiple logistic regression analysis of control study conducted in patients using stably methadone over 2 years demonstrated that the major risk factor of non-adherence was using heroin while taking methadone (aOR = 12, 4; 95% CI: 4, 19 - 36, 7, p < 0, 001) and giving up methadone above 3 days during 3 months (aOR = 18, 5; 95% CI: 7, 3 - 47, 1; p < 0, 001).