Methadone maintenance treatment and survival of schizophrenic patients with a lifetime comorbid substance use disorders: a long-term follow-up study

Abstract

Background Methadone maintenance treatment (MMT) remains the most widely used effective therapeutic approach for opioid use disorders. However, there is paucity of empirical data regarding the relationship between the MMT and survival of subjects with schizophrenia.

Aim The aim of this study was to examine the effect of MMT on the long-term survival of subjects with schizophrenia and a lifetime comorbid substance use disorders.

Methods The charts of 277 consecutive subjects admitted in our center during a period from January 1, 2002 to February 1, 2007 were assessed. Psychiatric diagnoses have been established according to international classification of diseases and health related problems-10th edition (ICD-10). The risk of all-cause mortality was assessed by Cox proportional-hazards regression models, including time-dependent covariates.

Results Out of MMT subjects, 31 (11.2%) had mental and behavioral disorders due to multiple psychoactive substance use, 5 (1.8%) had mental and behavioral disorders due to use of opioids. All of 13 (4.7%) subjects with opioid use disorders were treated. MMT has been found to be predictive of lower long-term survival, in time-independent (hazard ration [HR] = 1.88; 95%CI: 1.06-3.37; p<.05) and in time-dependent adjusted models (HR = 2.01; 95%CI: 1.21-3.60; p<.05). MMT daily dose of <120 mg (adjusted HR = 1.83; 95%CI: .95-3.54) and MMT daily dose of ≥120 mg (adjusted HR = 2.70; 95%CI: .97-7.54) were associated with less long-term survival, all compared with no lifetime MMT (p<.046).

Conclusions Among subjects with schizophrenia and a lifetime comorbid substance use disorders, overall mortality was higher in those who received lifetime MMT, then in patients without MMT.

Keywords:

• Methadone maintenance treatment
• schizophrenia
• all-cause mortality
• long-term follow-up
• Cox proportional-hazard regression model

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval and consent to participate

The authors confirm that the submitted study was conducted according to the WMA Declaration of Helsinki - Ethical Principles for Medical Research Involving Human Subjects. The study was approved by the IRB.

Authors’ contributions

YG designed the study, wrote the protocol and the first draft of the manuscript and undertook the statistical analysis and interpretation of data. EZS and KND critically reviewed the manuscript. MBT managed the literature searches and analyses. All the authors contributed to, and have approved, the final manuscript.