Response rates of Victorian general practitioners to a mailed survey on miscarriage: randomised trial of a prize and two forms of introduction to the research

Aims: To identify whether the form of introduction to a study and knowledge of a substantial prize influence the response rate of general practitioners (GPs) to a postal survey. Methods: A postal survey of 700 randomly selected Victorian GPs concerning management of early pregnancy bleeding and miscarriage, incorporating two randomised-controlled trials of recruitment methods; analysis of response rates and costs at 4 weeks and 11 weeks. Results: The response rate was 61.5% of eligible participants. Doctors made aware of a prize were more likely to respond in the first four weeks (difference in response rate 10.2%, 95% confidence interval (CI) 2.8% - 17.6%). This difference diminished after the first four weeks. Doctors introduced to the survey by a telephone call were no more likely to respond than those introduced by a postcard. The use of a postcard saved 73% of the cost of introducing the survey by telephone. Female doctors were more likely than males to reply (difference 12.3%. 95% CI 4.7% - 19.9%). Rural doctors were no more likely to reply than urban doctors. Very few doctors (16.2%) completed a Practice Assessment activity associated with the survey. Conclusions A valuable prize will accelerate response to a survey by GPs, thereby reducing the costs of follow-up. The cost of telephoned introductions is not justified, when compared with a brief written introduction.