Dynamic analysis of change in opioid use, cocaine use, and peer deviancy in methadone maintenance

Abstract

The present analysis was conducted to reveal nonlinear dynamic relationships among opioid use, cocaine use, and peer deviancy and the effect of attending counseling session for clients undergoing methadone maintenance. A model for DATAR clients was generated using an empirically based dynamic model. The present analysis implemented Courtney Brown's (1991) methodologies in estimating (a) overall fit of the model to data using pseudo $\rm R\sp2,$ (b) parameters for a set of differential equations using nonlinear least $\rm R\sp2,$ and (c) contribution of each parameter on overall fit using chi-square. Three features of the results deserve special attention. First, there were sharp drops in opioid use and cocaine use during 0 to 1 month period. Second, peer deviancy steadily decreased over three months during the treatment. Third, an equilibrium marsh was detected from the analysis of 1 to 3 months data in an approximate region of 0 to around 10 on frequency of monthly opioid use, 0 to around 15 on frequency of monthly cocaine use, and the bottom 35 percent on the peer deviancy composite scale. These findings suggest that treatment continued to affect clients' recovery throughout the three months and that process of recovery at 0 to 1 month and 1 to 3 months are indeed different.