Opening the black box of cancer patients' quality-of-life change assessments: a think-aloud study examining the cognitive processes underlying responses to transition items.

Transition items are a popular approach to determine the clinical significance of patient-reported change. These items assume that patients (1) arrive at a change evaluation by comparing posttest and pretest functioning, and (2) accurately recall their pretest functioning. We conducted cognitive think-aloud interviews with 25 cancer patients prior to and following radiotherapy. Two researchers independently analysed their responses using an analysis scheme based on cognitive process models of Tourangeau et al. and Rapkin and Schwartz. In 112 of the 164 responses to transition items, patients compared current and prior functioning. However, in 104 of these responses, patients did not refer to their functioning at pretest and/or posttest according to transition design's first assumption, but rather used a variety of time frames. Additionally, in 79 responses, the time frame employed and/or description of prior functioning provided differed from those employed in the corresponding pretest items. Transition design's second assumption was therefore not in line with the patients' cognitive processes. Our findings demonstrate that in interpreting transition assessments, one needs to be aware that patients provide change assessments, which are not necessarily based on the cognitive processes intended by researchers and health care providers.