Abstract
BACKGROUND: Treatment-related late effects can worsen over time among cancer survivors. Such worsening health states may trigger changes in internal standards, values, or conceptualization of quality-of-life (QOL). This "response-shift" phenomenon can jeopardize the validity of QOL assessment, and misrepresent QOL comparisons over time. This study tested response-shift effects in reporting future-health concerns among childhood cancer survivors who experienced progression in chronic health conditions (CHCs). METHODS: 2310 adult survivors of childhood cancer from St. Jude Lifetime Cohort Study completed a survey and clinical assessment at two or more timepoints. Based on 190 individual CHCs graded for adverse-event severity, global CHC burden was classified as "progression" or "non-progression". QOL was assessed using the SF-36(TM) eight domains and physical- and mental-component summary scores (PCS, MCS). A single global item measured concerns about future health. Random-effects models comparing survivors with and without progressive global CHC burden (progressors vs. non-progressors) evaluated response-shift effects (recalibration, reprioritization, reconceptualization) in reporting future-health concerns. RESULTS: Compared with non-progressors, progressors were more likely to de-emphasize (or downplay) overall physical and mental health in evaluating future-health concerns (p-values<0.05), indicating recalibration response-shift, and more likely to de-emphasize physical health earlier rather than later in follow-up (p-value<0.05), indicating reprioritization response-shift. There was evidence for a reconceptualization response-shift with progressor classification associated with worse-than-expected future-health concerns and physical health, and better-than-expected pain and role-emotional functioning (p-values<0.05). CONCLUSION: We identified three types of response-shift phenomena in reporting concerns about future health among childhood cancer survivors. Survivorship care or research should consider response-shift effects when interpreting changes in QOL over time.