English abstract
Objectives: We sought to determine the main factors related to relapse in patients with
substance-related disorders (SRDs) who received methadone maintenance therapy
(MMT) using decision tree (DT) analysis. Methods: We conducted a cross-sectional
study of 4175 patients referred to the 45 MMT centers in Kermanshah province,
west of Iran. We included all patients who were under MMT for at least one year. All
information was collected through an interview by a psychologist. Descriptive statistics
and univariate and multiple regression models were used in statistical analysis. The Gini
index was calculated to determine the cut-off point of nodes. We used the Classification
and Regression Trees algorithm to create the DT. Results: The relapse rate was 76.6%
for all participants, with no significant gender differences. The DT resulted in a five-level
model of significant factors affecting substance abuse relapse. These included lower cost
for buying substances, lower age at first substance use, history of quitting substances
without medication, frequency of substances utilization per month, and frequency of
methadone therapy. Conclusions: Knowing the main factors associated with substance
abuse relapse could be important for health care providers to make better decisions for
improving the treatment outcomes of SRDs.
