Higher monetary incentives led to a lowered response rate in ambulatory patients: a randomized trial

Monetary incentives can increase response rate in patient surveys, but calibration of the optimal incentive level is required. Our aim was to assess the effect of different monetary incentives on response rates to calibrate the optimal monetary incentive for ambulatory patients.

A patient-randomized trial was performed in which targeted individuals received different gift vouchers (€5.00, €7.50, €10.00, and €12.50) on completion of a survey and interview. Eligible patients (diagnosed type 2 diabetes, over 18 years) were recruited from primary care practices.

The response rate for the €12.50 incentive was lower compared with both the €7.50 and the €10.00 incentive [odds ratio (OR) = 0.60 and OR = 0.58]. A nonlinear model yield a better fit than a linear model. Within the observed range of incentive levels, an overall decrease in response rate was found.

High monetary incentives are not only inefficient but also less effective.