A comparison of methods of recruitment to a health promotion program for university seniors

Participant recruitment is an understudied part of health research. It can be a limiting factor and can affect the external validity of a study. This study compares two recruitment methods, active and passive, used to recruit university seniors into a health promotion study.

During active recruitment, 3,787 seniors were telephoned and asked to participate. During passive recruitment, 5,644 seniors were mailed literature and asked to respond if interested.

During active recruitment, 1,680 h were spent on the phone, 341 participants were measured, and 161 entered the study, at a cost of $79 per participant. During passive recruitment, 970 h were spent on the phone, 238 participants were measured, and 178 entered the study, at a cost of $45 per participant. The active method had a higher recruitment rate (9% vs 4%) and attrition rate (53% vs 25%) than the passive method.

In conclusion, neither recruitment method was ideal. Those recruited with the passive method reported more physical activity and had lower blood pressures, suggesting a self-selection bias. Active recruitment produced a more representative sample and a higher recruitment rate. Passive recruitment was less expensive and led to a lower attrition rate. Conclusions are limited because these are uncontrolled comparisons, not a controlled study.