15-Year survival and retention of patients in a general hospital-affiliated methadone maintenance treatment (MMT) center in Israel

https://doi.org/10.1016/j.drugalcdep.2009.09.013Get rights and content

Abstract

We have extended our previous 10-year follow-up study of MMT retention for another 5 years and added data on survival of all patients ever admitted to our MMT clinic (6/1993 to 6/2007). Data were calculated from admission to MMT until leaving, death, or study closure (6/2008). Ninety-four of a total of 613 patients (4711.6 person-years [py]) died. Cancer was the primary cause of death for those who remained in treatment, and overdose for those who left MMT. Longer survival (p = 0.051) with a trend for a lower mortality rate (p = 0.08) was noted among the 464 patients who stayed in treatment ≥1 year (1.8/100 py), compared with the 149 patients who left MMT <1 year (2.6/100 py). Predictors of survival in multivariate analyses were younger age (<40 years) at admission, living with a spouse/partner, being hepatitis B sera-negative, not abusing benzodiazepines on admission (interaction effect), not being referred directly from hospitalization to MMT, and not leaving the MMT program for hospitalization. The two latter variables also predicted longer retention, as did a high methadone dose (≥100 mg/d), no opiate and, no benzodiazepine abuse after 1 year and either having any DSM-IV-TR Axis I, or no Axis I&II psychiatric diagnoses. Unlike retention, mortality was associated with pre-treatment severity and comorbidities thus only partially reflects MMT outcome (opiate abstinence and treatment success). Benzodiazepine abuse reduced both retention and survival, emphasizing the high priority that should be given to stopping it.

Introduction

Opiate addiction is a chronic relapsing disorder characterized by a high mortality rate (Bargagli et al., 2001, Orti et al., 1996, Preti et al., 2002, Frischer et al., 1997, Sanchez-Carbonell and Seus, 2000) due to several possible complications (e.g., drug overdose and infectious disease, mainly HIV, hepatitis B and hepatitis C) as well as criminal behavior (Jow et al., 1982). To date, methadone maintenance treatment (MMT) is the most effective therapeutic approach to narcotic addiction (NIH Consensus Statement, 1997), and one that is strongly associated with harm reduction, a decrease in death rate, a reduction of opiate abuse, as well as a reduction of other complications. The death rate in this population, however, is still higher than that of the general population. Data comparing the death rate of patients who stayed in MMT vs. those who left are still limited and controversial (Ward et al., 1996, Amato et al., 2005); the latest published study, from Norway, reported a lower death rate for patients in MMT (Clausen et al., 2008). In Israel, the number of reported deaths due to any drug abuse were 54 for 1998, 93 for 1999 and 85 for 2000 with age-adjusted mortality rates of 0.78, 1.37 and 1.22, respectively (according to the International Classification of Diseases, 10th Revision (ICD-10) diagnoses of F10–F19) (Israeli Ministry of Health, 2009).

MMT success is characterized by long retention, and predictors for retention have been well studied (Peles et al., 2006a, Strain et al., 1999, Caplehorn et al., 1994). In the current study, we compared long-term retention and patients’ survival in a cohort of former heroin addicts admitted to a MMT program from its establishment in 1993 until 2008. The clinic is located within Tel Aviv Sourasky Medical Center (TASMC), a large, municipal university-affiliated medical center (1100 beds). Thus some patients were admitted to the clinic directly from hospital wards.

Our aim was to characterize predictors for long-term survival among MMT patients, a little known feature of this population. Since the clinic includes patients with a variety of comorbid illnesses, we hypothesized that patients who arrived directly following a period of hospitalization (indicating a worse medical condition at admission than those admitted from the community) would show a poorer survival rate. We also expected that patients who dropped out of treatment by their own decision or were expelled (e.g., due to violent behavior or selling/buying drugs within the clinic), would have poorer survival rates compared with patients who stayed in treatment. Retention is one of the most common and acceptable measurement of MMT outcome (for review see Amato et al., 2005), but predictors for retention and survival in the same cohort have never been studied, and showing a positive association between them would support the validity of retention as an important measurement of outcome.

Section snippets

Methods

The study was approved by the TASMC IRB (Helsinki committee) [217-7/05].

Patients

A total of 613 patients were studied (451 males and 162 females) with a mean age on admission of 37.6 ± 8.9 (ranged 18–75) years. The overall mortality rate was 2.0/100 py (94 deaths, 4711.6 py) (Table 1). The death rate did not differ between the 285 patients who never left MMT (2.2/100 py, 42 deaths, 1891.2 py), the 95 who were readmitted (1.9/100 py, 18 deaths, 927.7 py) and the 233 who left treatment (1.8/100 py, 34 deaths, 1892.8 py). The mortality rate was, however, lower as a trend among

Discussion

The collective mortality rate of our 613-patient study group was 2.0/100 py, with no differences between those who stayed and those who left MMT. However, patients who stayed in treatment for at least 1 year had a longer mean survival and a trend of lower mortality than those who left before 1 year. The mortality rate did not differ between patients who stayed, between those who left, or those who left and then were readmitted to MMT clinic. In general, studies have found a better survival for

Role of funding source

This research was supported by internal funds (M.A.).

Contributors

All authors have been personally and actively involved in substantive work leading to the report, and will hold themselves jointly and individually responsible for its content.

Conflict of interest

None reported.

Acknowledgements

Many thanks to Ziona Haklai, Head of Health Information Department, Ministry of Health, for providing the detailed list of causes of deaths data in Israel. Esther Eshkol is thanked for extensive editorial assistance.

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