Feasibility, psychometric performance, and stability across modes of administration of the CARES-SF

BACKGROUND:: The primary objective was to investigate the validity and reliabilityof the Cancer Rehabilitation Evaluation System-Short Form (theCARES-SF) as a quality of life instrument in clinical trials[10]. PATIENTS AND METHODS:: A heterogeneous sample of 485 cancer patients completed theCARES-SF before treatment (T1), one month later (T2), and threemonths following T2 (T3). At T3 the patients completed the questionnaireeither by mail, in a telephone interview, or in the clinic.A sub sample of patients completed the CARES-SF a fourth time(T4) one week following T3, for purposes of test-retest reliabilityestimation. RESULTS:: On average, the CARES-SF required 11 minutes for completionand could be completed by 90% of the patients without assistance.However, 82% of the patients re ported difficulty with at leastone item. Multitrait scaling analysis and factor analysis generallyconfirmed the hypothe-sized scale structure. Internal consistencyreliability coefficients exceeded the 0.70 criterion for fourof six multi-item scales. The test-retest reliability coefficientsof the six scales were above 0.70. No systematic differenceswere found in the psychometrics of the CARES-SF across administrationconditions. In the mail condition the proportion of missingitems was significantly higher, and patients reported havingsignificantly more problems than in both the telephone and in-clinic condition. According to expectation, selective scalesdistinguished clearly between patients differing in diseasestage, performance status, treatment modality and tumor response.Additionally, selective scales were responsive to changes inhealth status over time. CONCLUSION:: These results lend support to the reliability and validity ofthe CARES-SF in assessing the quality of life of patients withcancer. At the same time, efforts to refine the questionnaireare recommended. Cancer, CARES-SF, quality of life, validation