Development and validation of a disease-specific quality of life questionnaire (EQOL) for potentially curable patients with carcinoma of the esophagus

The objective was to develop, pretest and validate a disease-specific quality of life questionnaire for potentially curable patients with esophageal carcinoma, for use with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) in order to assess the quality of life associated with the various treatment modalities available for this disease. Questionnaire development phase Patients were enrolled in three centres. Literature reviews, patients, family members, and health care professionals generated 195 items: symptoms (55); emotions (53); physical functioning (17); activities of daily living (ADL) (48); and leisure/social (22). Thirty-eight patients identified items of importance and assigned importance ratings on a 5-point Likert scale. Impact scores were calculated as frequency times mean item importance. Item impact scores<20/100 were excluded. Pearson's correlation co-efficients compared domains with the Medical Outcomes Study SF-20 (MOS SF-20). Fifteen items remained. Questionnaire validation phase EORTC QLQ-C30, Esophageal Quality of Life Questionnaire (EQOL), MOS SF-36 and a Global Rating of Change Questionnaire were completed at baseline, 1 week after baseline but prior to any treatment, 1 month, 3 months, and 6 months after treatment began. Reliability was assessed using paired samples correlations. Responsiveness was assessed between mean scores of changed and unchanged patients, and a responsiveness index was calculated. The MOS SF-36 was used for criterion validity. Construct validity included four a priori predictions. Sixty-five patients were enrolled in four centres in the validation phase. Paired samples correlations were high for all domains (0.749-0.889) indicating good reliability. Symptom, physical function and social domains were responsive to change at all time intervals (P<0.05). Emotional function was responsive at 1 and 3 months, activities of daily living (ADLs) at 1 and 6 months. Magnitude of change was significant when direction of change was stated. Between better and worse, magnitude of change was significant in all domains except at 6 months in symptoms, emotional and physical domains. The minimal clinically important difference was consistently around 0.5 for all domains. Minimal, moderate and large effect ranges were established. Only 2/16 time intervals had poor correlations with the SF-36, establishing criterion validity. Of the four a priori predictions for construct validity, only the second part of one prediction, in the emotional function domain, was not confirmed. We have developed a 15-item questionnaire (EQOL) which has good reliability, responsiveness and validity and is now in use in studies in Canadian centres with the EORTC QLQ-C30.