Effect of Advance Telephone Prompting in a Survey of GDPs

Objectives: To evaluate the effect an advance telephone prompting strategy, via a dental practice receptionist, had on the response rate to a postal self-completed questionnaire and to estimate the additional and incremental cost of such a strategy. Methods: The study took the form of a randomised controlled trial and incremental cost analysis. General dental practitioners with an NHS health board list number were randomly selected from the Dental Services (NHS Dental primary care), Scotland to receive a questionnaire. They were also randomly allocated to the advance-prompted or non-prompted arms of the trial. Questionnaires were colour coded to identify advance-prompted and non-prompted respondents. Individual respondents were anonymous and therefore targeted non-respondent follow-ups were not possible. The total cost of this strategy was estimated and an incremental cost estimate ratio (ICER) was calculated. Results: The response rates were 53% in the advance telephone prompt group and 40% in the non-prompted group. The difference of 13% was found to be statistically significant, p = 0.026. The total additional cost of this strategy was found to be ₤74.00 and the ICER was calculated to be ₤4.93 for each additional response. Conclusion: Advance telephone prompting of General Dental Practitioners, via the practice reception, was found to significantly improve the response rate to a postal self-completed questionnaire. This may be a cost effective way of improving response rates to postal questionnaires, particularly where a low response rate is expected and where targeted follow-up of non-respondents is not possible.