Abstract
PURPOSE: We compared health-related quality of life (HRQOL) between adult survivors of childhood cancer and siblings by investigating the mediating role of emotional distress on HRQOL assessment, and examining the extent to which emotional distress affected the item responses of HRQOL measures given the same underlying HRQOL (i.e., measurement non-invariance). METHODS: Cancer survivors (7103) and siblings (390) enrolled in Childhood Cancer Survivor Study who completed the SF-36 measuring HRQOL and the Brief Symptom Inventory-18 measuring anxiety, depression, and somatization were analyzed. Multiple Indicators & Multiple Causes modeling was performed to identify measurement non-invariance related to emotional distress on the responses to HRQOL items. Mediation analysis was performed to test the effects of cancer experience on HRQOL accounting for the mediating role of emotional distress. RESULTS: Twenty-nine percent, 40%, and 34% of the SF-36 items were identified with measurement non-invariance related to anxiety, depression, and somatization, respectively. Survivors reported poorer HRQOL than siblings in all domains (ps < 0.05), except for pain. Other than physical functioning and general health perceptions, poorer HRQOL was explained by the mediating role of emotional distress (ps < 0.05). CONCLUSIONS: Differences in HRQOL between survivors and siblings appear due, in part, to the mediating effect of emotional distress through which cancer experience influences the responses to HRQOL measures. IMPLICATIONS OF CANCER SURVIVORS: Interventions to treat emotional distress may improve cancer survivors' HRQOL.