Using a symptom-specific instrument to measure patient-reported daily functioning in patients with cancer

Objectives Improving, stable, or deteriorating patient functioning is critical to assess in cancer care and in oncology clinical trials. We evaluated the performance of the six-item interference subscale of the MD Anderson Symptom Inventory (MDASI) compared with two commonly used patient-reported measures of functioning as a reference: the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and the Medical Outcomes Study Short Form 12-item health survey (SF-12). Methods In this secondary analysis of two databases, MDASI versus QLQ-C30 (431 multiple myeloma patients) and MDASI versus SF-12 in solid tumours (285 lung and 91 gastrointestinal cancer patients), we used Pearson correlations to test relationships of four SF-12 and five QLQ-C30 functioning subscales with MDASI total interference (MDASI-INTFER), physical (MDASI-WAW), and affective (MDASI-REM) subscales. We used area under the curve (AUC) to quantify ability to differentiate performance status levels, and Glass Delta effect size (ES) and standardised response mean to evaluate responsiveness to aggressive cancer treatment. Results MDASI-WAW was strongly correlated with QLQ-C30 and SF-12 physical subscales across all three cancer types (all r ≥ 0.7, P < 0.0001). The MDASI-WAW displayed AUCs that were similar to the physical functioning scales of QLQ-C30 and SF-12 (>0.7). MDASI-WAW responsiveness was equivalent to the SF-12 physical functioning subscale for chemoradiotherapy (ES = 0.72 for MDASI-WAW; 0.55 for SF-12), surgery (ES = 0.92 for MDASI-WAW; 0.97 for SF-12), and worsening of general health (ES = 1.22 for MDASI-WAW; 1.05 for SF-12). Conclusions MDASI interference is a valid measure of symptom-related functional impairment. The three-item MDASI-WAW subscale is comparable to the SF-12 in responsiveness to functional deterioration during aggressive cancer treatment.