Use of incentives to increase compliance for TB screening in a population of intravenous drug users. Vancouver Injection Drug Use Study Group

Abstract

Setting: Intravenous drug users (IDUs) represent a high risk group for dual human immunodeficiency virus (HIV) and tuberculosis (TB) infection. Screening with TB skin testing has therefore been suggested in this group. Subjects' compliance for returning to have TB skin test results read is a major problem. In the setting of a needle exchange program we evaluated the role of financial incentives to increase compliance.

Methods: We evaluated the role of giving a small financial incentive of Can $5 to subjects if they returned to have their purified protein derivative (PPD) skin test read. IDUs who had previously been skin-tested were compared with IDUs drawn from a similar population who, prospectively, were offered a financial incentive.

Results: During the initial period 558 subjects were evaluated and no incentive was offered. During the second phase of the study 549 IDUs were assessed but were also offered Can $5 if they returned to have their skin test read. Use of incentives increased compliance from 43% to 78% (P = 0.001). During the same period three active cases of TB were also diagnosed.

Conclusions: We suggest that use of financial incentives can increase the return of IDUs to have their skin tests read. Further studies are required to assess the efficacy of follow-up interventions, especially the use of isoniazid chemoprophylaxis.