Clinical trial participants' experiences of completing questionnaires: a qualitative study

Objectives To improve clinical study developments for elderly populations, we aim to understand how they transfer their experiences into validated, standardised self-completed study measurement instruments. We analysed how women (mean 78 +/- 8 years of age) participating in a randomised controlled trial (RCT) cognised study instruments used to evaluate outcomes of the intervention. Setting The interview study was nested in an RCT on chronic neck pain using common measurement instruments situated in an elderly community in Berlin, Germany, which comprised of units for independent and assisted-living options. Participants The sample (n=20 women) was selected from the RCT sample (n=117, 95% women, mean age 76 (SD +/- 8) years). Interview participants were selected using a purposive sampling list based on the RCT outcomes. Outcomes We asked participants about their experiences completing the RCT questionnaires. Interviews were analysed thematically, then compared with the questionnaires. Results Interviewees had difficulties in translating complex experiences into a single value on a scale and understanding the relationship of the questionnaires to study aims. Interviewees considered important for the trial that their actual experiences were understood by trial organisers. This information was not transferrable by means of the questionnaires. To rectify these difficulties, interviewees used strategies such as adding notes, adding response categories or skipping an item. Conclusions Elderly interview participants understood the importance of completing questionnaires for trial success. This led to strategies of completing the questionnaires that resulted in 'missing' or ambiguous data. To improve data collection in elderly populations, educational materials addressing the differential logics should be developed and tested. Pilot testing validated instruments using cognitive interviews may be particularly important in such populations. Finally, when the target of an intervention is a subjective experience, it seems important to create a method by which participants can convey their personal experiences. These could be nested qualitative studies. Trial registration number ISRCTN77108101807.