The present study of homeless non-treatment-seeking problem drug users was designed to complement and extend previous studies which focused exclusively on treatment-seeking homeless problem drug users. Data were available for 866 primary care patients with drug problems, 30% homeless and 70% housed.

In the 2 years prior to baseline, homeless participants had less chronic medical co-morbidity than problem drug users who were housed yet were significantly more likely to have used emergency department services, to have used them more frequently, and at higher cost. Compared to their housed counterparts, homeless participants were also more likely to have been admitted to specialized chemical dependency treatment and/or detoxification services, to have been arrested for a felony or gross misdemeanor, and to report having psychiatric problems in the prior 30 days.

Additional support may be necessary for homeless patients presenting in primary care to benefit from substance abuse treatment given their more severe drug use problems coupled with their co-morbid health, psychiatric, and psychosocial problems.