Questionnaire order significantly increased response to a postal survey sent to primary care physicians

OBJECTIVE: Primary care physicians are increasingly being asked to participate in postal surveys. Difficulties in achieving adequate response rates among physicians have been reported. We investigated the effect of two low-cost interventions on response to a primary care physician postal questionnaire. STUDY DESIGN AND SETTING: A 2x2 factorial trial was developed within the context of a national survey assessing views and practices of physicians regarding prostate-specific antigen testing. We evaluated questionnaire order (version 1: demographics first, version 2: topic-specific questions first) and written precontact. A national database of primary care physicians was compiled. One thousand five hundred ninety-nine physicians were randomly selected, stratified by health board, and randomized. RESULTS: 47.9% of eligible physicians completed a questionnaire. There was a statistically significant 5.1% higher response rate among physicians receiving version 1 of the questionnaire than those receiving version 2 (50.6% vs. 45.4%, P=0.05); the adjusted odds of response were significantly raised (odds ratio=1.24; 95% confidence interval=1.01-1.54). Precontact resulted in a nonsignificant 3.6% increase in response (49.8% vs. 46.2%; P=0.16). The interventions did not interact. CONCLUSION: Ordering questionnaires with general questions first can significantly increase response rates, whereas precontact can achieve a modest increase. These strategies may enhance response while adding little to the cost of a physician survey.