Challenges in Using Recommended Quality of Life Measures to Assess Fluctuating Health: A Think-Aloud Study to Understand How Recall and Timing of Assessment Influence Patient Responses.

backgroundIt can be challenging to measure quality of life to calculate quality-adjusted life-years in recurrent fluctuating health states, as quality of life can constantly change. It is not clear how patients who experience fluctuations complete measures and how assessment timing and recall influence responses.

objectiveWe aimed to understand how patients with fluctuating health complete widely recommended and commonly used measures (EQ-5D-5L, EORTC QLQ-C30 and SF-12) and the extent to which the recall period ('health today', 'past week' and 'past 4 weeks') and timing of assessment influence the way that patients complete these questionnaires.

methodsTwenty-four adult patients undergoing chemotherapy for urological, gynaecological or bowel cancers in the UK participated in think-aloud interviews, while completing the measures, completed a pictorial task illustrating how quality of life changed during the chemotherapy cycle and took part in semi-structured interviews. Transcripts were analysed using constant comparison.

resultsPatients were consistent in describing their quality of life as changing considerably throughout a chemotherapy cycle. The shorter recall period of 'health today' does not adequately represent patients' quality of life because of fluctuations, patients remarked they could give a different answer depending on the timing of assessment, and many struggled to combine the "ups and downs" to answer measures with longer recall ('past week' and 'past 4 weeks'). Across all measures, patients attempted to provide averages, adopt the peak-end rule or focus on the best part of their experience. Patients commonly used more than one approach when completing a given questionnaire as well as across questionnaires.

conclusionsPatients who experience recurrent fluctuations in health are unable to provide meaningful responses about their quality of life when completing quality-of-life measures due to the recall period and timing of assessment. The use of such responses to calculate health state values in economic evaluations to inform resource allocation decisions in fluctuating conditions must be questioned.