Evaluation of index and profile measures of health status in a randomized controlled trial - Comparison of the medical outcomes study 36-item short form health survey, EuroQol, and disease specific measures

OBJECTIVES. The authors compare two generic measures of health status with disease-specific measures in a randomized controlled trial of transurethral resection of the prostate with laser vaporization prostatectomy for benign prostatic hypertrophy. METHODS. Patients entered into the trial completed the following questionnaires prior to treatment and at follow-up at 3 months and 1 year. The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) is a generic measure that produces an eight-dimension profile as well as two summary measures of health status (the physical component score and the mental component score). The EuroQol provides two single index measures of health status; one intended to convey the utility (or lack of) that an individual derives from his or her own health state compared with alternative states and a second simple visual analog scale ''thermometer'' of health status. The American Urological Association symptom score and the Bothersome index are disease-specific indices of health status for use specifically with benign prostatic hypertrophy patients. RESULTS. The EuroQol indicates no statistically significant improvements with time for either arm of the trial. The SF-36 physical and general health perceptions domains indicates statistically significant improvements for the transurethral resection of the prostate arm alone at 3 months and 1 year, as do the physical summary score at the 3-month follow-up visit. The effect sizes of these improvements, however, are small, using standard criteria. In contrast, statistically significant differences are found with time for both transurethral resection of the prostate and laser prostatectomy on both disease-specific measures; which also indicate statistically significant superior outcome for the transurethral resection of the prostate arm compared with the laser arm. CONCLUSIONS. The results indicate that the disease-specific measures are more sensitive to change than the generic measures of outcome. Possible explanations for this are discussed.