A randomized trial of survey participation in a national random sample of general practitioners and gynecologists in France

Background: Healthcare professionals play a critical role in women's choice of contraceptive methods. However, national surveys on sexual and reproductive health (SRH) among physicians are rare and present low participation rates. We conducted a randomized trial to test for the effectiveness of three interventions to improve survey participation of private physicians delivering reproductive health services in France. Methods: The study comprised a national random sample of 500 general practitioners and 500 gynecologists working in private offices. All received a postal invitation to participate either by completing a paper, phone or online questionnaire. Physicians were randomly assigned to six groups to test for the effect of three interventions: a non-monetary incentive in the form of a scientific book, telephone contact, and the possibility of completing the questionnaire by phone. Results: Overall, 362 questionnaires were collected (26 online, 2 by phone) and 58 physicians were ineligible. The completion rate increased from 26.7% in physicians who received no intervention to 42.7% in those who received the book and a phone call. The phone call increased the completion rate by 11% percentage points (P= 0.01), while the book had no significant effect. Results from multivariate logistic regressions also indicate that gynecologists (OR = 1.6) and female physicians (OR = 1.5) were more likely to participate than others. Conclusion: The results suggest that phone calls substantially increase participation of physicians in sexual and reproductive health surveys but have little impact on sampling distortion. Differentials in response rates by physicians' characteristics should be considered in future SRH studies among physicians.