The impact of substance abuse treatment modality on birth weight and health care expenditures.

During the 1990s, substance abuse treatment programs were developed for pregnant women to help improve infant birth outcomes, reduce maternal drug dependency and promote positive lifestyle changes. This study compared the relative impact of five treatment modalities--residential, outpatient, residential/outpatient, methadone and detoxification-only--on infant birth weight and perinatal health care expenditures for a sample of 445 Medicaid-eligible pregnant women who received treatment in Massachusetts between 1992 and 1997. Costs and outcomes were measured using the Addiction Severity Index and data from birth certificates, substance abuse treatment records and Medicaid claims. Multiple regression was used to control for intake differences between the groups. Results showed a near linear relationship between birth weight and amount of treatment received. Women who received the most treatment (the residential/outpatient group) delivered infants who were 190 grams heavier than those who received the least treatment (the detoxification-only group) for an additional cost of $17,211. Outpatient programs were the most cost-effective option, increasing birth weight by 139 grams over detoxification-only for an investment of only $1,788 in additional health care and treatment costs. A second regression using five intermediate treatment outcomes--prenatal care, weight gain, relapse, tobacco use and infection--suggested that increases in birth weight were due primarily to improved nutrition and reduced drug use, behaviors which are perhaps more easily influenced in residential settings.