Predictors of the degree of drug treatment coverage for injection drug users in 94 metropolitan areas in the United States of America.

Aims: A prior study concluded that drug treatment coverage, defined as the percentage of injection drug users in drug treatment, varied from 1 percent to 39 percent (median 9 percent) in 96 metropolitan statistical areas (MSAs) in the United States. Here, we determine which metropolitan area characteristics are associated with drug treatment coverage.

Methods: We conducted secondary analysis of official data, including the number of injection drug users in treatment and other variables, for 94 large US MSAs. We estimated the number of injection drug users in these metropolitan areas using previously described methods. We used lagged cross-sectional analyses where the independent variables, chosen on the basis of a Theory of Community Action, preceded the dependent variable (drug treatment coverage) in time. Predictors were determined using ordinary least squares multiple regression and confirmed with robust regression.

Results: Independent predictors of higher drug treatment coverage for injectors were: presence of organisations that support treatment (unstandardized beta=1.64; 95 percent CI .59 to 2.69); education expenditures per capita in the MSA (unstandardized beta=.12; 95 percent CI -.34 to 2.69); lower percentage of drug users in treatment who are non-injection drug users (unstandardized beta=-0.18; 95 percent CI -0.24 to -0.12); higher percentage of the population who are non-Hispanic White (unstandardized beta=.14; 95 percent CI .08 to .20); lower per capita long-term debt of governments in the metropolitan area (unstandardized beta=-0.93; 95 percent CI -1.51 to -0.35).

Conclusions: In conditions of scarce treatment coverage for drug injectors, an indicator of epidemiologic need (the per capita extent of AIDS among injection drug users) does not predict treatment coverage, and competition for treatment slots by non-injectors may reduce injectors' access to treatment. Metropolitan finances limit treatment coverage. Political variables (racial structures, the presence of organisations that support drug treatment, and budget priorities) may be important determinants of treatment coverage for injectors. Although confidence in these results would be higher if we had used a longitudinal design, these results suggest that further research and action that address structural, political, and other barriers to treatment expansion are sorely needed.