One-Year and Cumulative Retention as Predictors of Success in Methadone Maintenance Treatment: A Comparison of Two Clinics in the United States and Israel

ABSTRACT

Outcome predictors between two methadone maintenance treatment clinics in Tel-Aviv, Israel, and Las Vegas, Nevada, were determined by comparing patients' characteristics. All patients admitted to the two clinics (302 from Las Vegas and 492 from Tel-Aviv) were studied with respect to variables at admission and follow-up. Las Vegas patients were older, contained more females, had more hepatitis C positive markers, and more urine analyses that were positive for cocaine, amphetamines, and tetrahydrocannabinol (THC) on admission than the Tel-Aviv patients. After 1 year, Tel-Aviv patients had higher retention (73.6% vs. 61.6%) and similar opiate abstinence (65.8% vs. 64.9%) compared to Las Vegas patients. Predictors for cumulative retention (Cox regression) for both clinics were higher methadone dosages greater than or equal to 100 mg/day (Tel-Aviv OR [odds ratio] = 2.1, 95% confidence interval [CI] = 1.6–2.9; Las Vegas OR = 1.8, 95% CI = 1.3–2.5). Also, in Tel-Aviv, predictors were no opiate use after 1 year (OR = 1.7, 95% CI = 1.4–2.2) and no benzodiazepine after 1 year, and in Las Vegas no cocaine and no amphetamines after 1 year and age less than or equal to 30 years. The two major predictors in the two clinics were successful in both outcomes: 1 year retention and opiate abstinence.

KEYWORDS:

• Methadone maintenance treatment
• countries' differences
• Kaplan-Meier analyses
• retention
• predictors

Supported by K05-DA00049 (MJK), NIH-NIDA P60-05130 (MJK), and internal funds (MA).

Notes

^‡Medical Director in Tel-Aviv (3 times/week, 8 hours/week).

^§Medical Director in Las Vegas.

∗Analysis of varience.

∗∗Fisher's exact test, excluding the younger than 8 years group.

∗∗∗Fisher's Exact test, excluding the not tested group.

∗Fisher's Exact Test.

^aSignificant differences marked in bold.

∗For each variable category, the mean and 95% CI cumulative retention in treatment (Kaplan Meier) is presented in years, and the comparison between categories is presented by log–rank and significance (P value).

∗∗If patients left before 1 year, the last month in treatment was used. Excluding patients who stay less than 4 months.

∗Cox regression model included variables that were significantly associated with cumulative retention in the Kaplan-Meier analyses (P < .05). Odds Ratio (OR), 95% Confidence Interval (CI), and P values are presented.