Prospective validation of substance abuse severity measures from administrative data

Severity measures for clients in substance abuse treatment programs are becoming increasingly important as funders adopt payment systems linked to agency performance. Recently, two severity measures based on administrative data have been developed. This study validated these measures using prospective data.

Subjects were participants in the Drug Abuse Treatment Outcomes Study (adult or adolescent components) or the Substance Abuse and Mental Health Services Administration Medicaid Managed Behavioral Healthcare and Vulnerable Populations project (adult or adolescent chemical dependency components). Severity measures were calculated based on data obtained at entry into substance abuse treatment. The baseline severity measures were included along with age, gender, and race/ethnicity in logistic regression models predicting abstinence at follow-up for alcohol use, marijuana use, cocaine use, or heroin use.

For adults, the severity measures were highly statistically significant (p<0.001) for all models in both data sets, indicating that adults with higher severity were more likely (and much more likely in many cases) to use alcohol, marijuana, cocaine, or heroin at the follow-up interview than were those with lower severity. For adolescents, the severity measure was highly statistically significant (p<0.001) for marijuana in both data sets and for alcohol in the Medicaid data set.

Baseline severity measures were powerful predictors of abstinence at follow-up. These measures, derived from routinely available electronic records, appear to have noteworthy predictive validity. The severity indicators can be used for administrative purposes such as risk-adjustment when examining treatment agency performance.