Changes in the characteristics and levels of comorbidity among new patients into methadone maintenance treatment program in British Columbia during its expansion period from 1998-2006.

We described the changing characteristics and comorbidity levels of new patients into Methadone maintenance treatment (MMT) program in British Columbia, Canada, during its expansion period of 1998-2006. Analyses used administrative data. Generalized regression models were applied using Charlson Comorbidity Index (CCI) and Chronic Disease Score (CDS) as outcomes. 12,615 individuals initiated MMT during 1998-2006, while their odds of having moderate CCI (1 ≤ CCI ≤ 4) and mean CDS increased by 60% and 11%, respectively, after adjusting for confounders. MMT entrants were presented with progressively higher levels of comorbidity, independent of other characteristics. Future MMT policies should address higher levels of comorbidity among new patients.