Evaluation of active and passive recruitment methods used in randomized controlled trials targeting pediatric obesity

Objective. Evaluate enrollment numbers, randomization rates, costs, and cost-effectiveness of active versus passive recruitment methods for parent-child dyads into two pediatric obesity intervention trials. Methods. Recruitment methods were categorized into active (pediatrician referral and targeted mailings, with participants identified by researcher/health care provider) versus passive methods (newspaper, bus, internet, television, and earning statements; fairs/community centers/schools; and word of mouth; with participants self-identified). Numbers of enrolled and randomized families and costs/recruitment method were monitored throughout the 22-month recruitment period. Costs (in USD) per recruitment method included staff time, mileage, and targeted costs of each method. Results. A total of 940 families were referred or made contact, with 164 families randomized (child: 7.2 +/- 1.6 years, 2.27 +/- 0.61 standardized body mass index [zBMI], 86.6% obese, 61.7% female, 83.5% Caucasian; parent: 38.0 +/- 5.8 years, 32.9 +/- 8.4 BMI, 55.2% obese, 92.7% female, 89.6% caucasian). Pediatrician referral, followed by targeted mailings, produced the largest number of enrolled and randomized families (both methods combined producing 87.2% of randomized families). Passive recruitment methods yielded better retention from enrollment to randomization (p < 0.05), but produced few families (21 in total). Approximately $91 000 was spent on recruitment, with cost per randomized family at $554.77. Pediatrician referral was the most cost-effective method, $145.95/randomized family, but yielded only 91 randomized families over 22-months of continuous recruitment. Conclusion. Pediatrician referral and targeted mailings, which are active recruitment methods, were the most successful strategies. However, recruitment demanded significant resources. Successful recruitment for pediatric trials should use several strategies.