Response burden is often defined as the effort required by the patient to answer a questionnaire. A factor that has been proposed to affect the response burden is questionnaire length, and this burden is manifested in, for example, response rate. Even though response burden is frequently mentioned as a reason for abridging questionnaires, evidence to support the notion that shorter instruments are preferable is limited.
This study aimed to accumulate, analyze, and discuss evidence regarding the association between response burden, as measured by response rate, and questionnaire length.
A systematic literature review and meta-analysis of studies reporting response rates in relation to questionnaire length was performed. A Cochran-Mantel-Haenszel test stratified by study using the Breslow-Day test was undertaken to investigate homogeneity of the odds ratios.
Thirty-two reports were identified, of which 20 were eligible for inclusion in the meta-analysis. Three studies used patient input as main outcome when evaluating response burden. In the meta-analysis, a general association between response rate and questionnaire length was found (P ≤ 0.0001). Response rates were lower for longer questionnaires, but because the P value for test of homogeneity was P = 0.03, this association should be interpreted with caution because it is impossible to separate the impact of content from length of the questionnaires.
Given the inherently problematic nature of comparing questionnaires of various lengths, it is preferable to base decisions on use of instruments on the content rather than the length per se.