Tracking and Locating Itinerant Subjects With a Rechargeable Incentive Card: Results of a Randomized Trial

Area of Science:

• Public Health Research
• Behavioral Science
• Health Services Research

Background:

• High participant attrition in field research compromises study validity and generalizability.
• Effective participant retention strategies are crucial for longitudinal studies.

Purpose of the Study:

• To compare the efficacy of rechargeable incentive cards (RICs) versus money orders (MOs) in enhancing participant engagement and follow-up contact.
• To assess the impact of these incentive methods on staff time and resource allocation in a substance abuser population.

Main Methods:

• A randomized controlled trial involving 303 substance abusers in Los Angeles.
• Participants were assigned to either an MO (control) or RIC (experimental) group for monthly $10 payments over 5 months.
• Study engagement (monthly calls) and 6-month follow-up rates were assessed, along with staff time for participant tracking and payments.

Main Results:

• RIC participants, particularly those with lower ability to defer gratification, made more monthly calls than the MO group.
• Six-month follow-up rates were comparable between RIC (75%) and MO (79%) conditions.
• The RIC method resulted in an average staff time saving of 39.8 minutes per participant.

Conclusions:

• Rechargeable incentive cards offer a modest improvement in study engagement and significant staff time savings for longitudinal public health research with itinerant populations.
• The cost-effectiveness of RICs is contingent on vendor pricing models and project scale.
• RICs present a viable alternative for improving participant retention and operational efficiency in public health studies.