Response rates to questionnaire-based studies in the contemporary dental literature: A systematic review

This systematic review aimed to investigate what is a reasonable response rate for dental questionnaire-based studies in recent literature and to assess the factors that affect the response rates.

We used MEDLINE/PubMed to search the dental literature of 2021 (January-October). Two reviewers independently assessed studies eligibility and extracted data using standardized electronic extraction form.

One hundred and seventy-two studies were eligible, of these a total of 149 response rates were reported from 133 studies, whereas the remaining 39 studies were excluded as they did not report response rates. The median response rate across the included studies was 77% (mean = 70.8%). We found significant negative correlation between the response rate and the actual number of distributed questionnaires (sample size) (r = -0.4127; P < 0.001). We also found an association between the response rate and the area of distribution, e.g., national or international (P = 0.0012). However, a wide variation was observed in the quality of information reported within this review and we did not find clear evidence of association between the response rate and other variables such as questionnaire piloting, number of questions in the questionnaire and the journal impact factor.

The findings of this systematic review confirm the association between the response rate and the sample size, where the response rate increases when the sample size less than 300 participants. In addition, a higher response rate could be achieved when the study conducted within the same institution (e.g., university).

Questionnaire-based research can provide answers to several questions that could not be answered by other types of research related to the field of dentistry, dental health practitioners and students' attitudes and behaviours and more. Questionnaire-based publications can effectively contribute to dental research; thus, dental journals should consider development of a minimum set of guidelines in the reporting of questionnaire-based manuscripts.