European Urology European Urology 42 (2002) 491±497 TheValuationof the International Prostate Symptom Score (IPSS) for Usein Economic Evaluations Esther T. Kok a , Joseph McDonnell a,* , Elly A. Stolk a , Herman J. Stoevelaar b , Jan J.V. Busschbach a On behalf of the Triumph Research Group Pan-European Expert Panel (Appendix A) a Institute for Medical Technology Assessment (iMTA), Erasmus University Rotterdam, P.O. BOX 1738, 3000 DR Rotterdam, The Netherlands b Department of Health Policy and Management, Erasmus University, Rotterdam, The Netherlands Accepted 27 August 2002 Abstract Objective: Lower Urinary Tract Symptoms (LUTS) suggestive of Benign Prostatic Obstruction (BPO) cause a reduction in quality of life, but the magnitude of that reduction cannot be estimated empirically. This is because survey instruments currently available merely sum the symptoms found, but do not value their impact on quality of life. It is therefore dif®cult to determine whether the effects of treatments for LUTS suggestive of BPO justify the costs. This complicates economic evaluations. Methods: Wevalued the impact on quality of life of patients with LUTS suggestive of BPO, by valuing health states de®ned by the International Prostate Symptom Score (IPSS) using the time trade-off (TTO). TTO values ranged from 1.0 for perfect health to 0.0 for the value of death, and can be used to calculate Quality-Adjusted Life Years (QALYs), the preferred outcome measure in health economics. Results: We reduced the number of health states de®ned by the IPSS using factor analysis. The resulting nine health states were valued by a representative sample of the general public (N  170) using TTO. The worst IPSS health state was valued at 0.87. Conclusion: The values for health states de®ned by the IPSS revealed that LUTS suggestive of BPO has a mild impact on quality of life. The valuation of the IPSS facilitates economic evaluations of treatments for LUTS suggestive of BPO, because QALYs (the preferred outcome measure in health economics) can be determined empirically. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Male; Cost±bene®t analysis; Quality-Adjusted Life Years; Prostatic hyperplasia; Factor analysis; Statistical 1. Introduction In clinical sciences, it is common to begin a clinical report with a description of the magnitude of the health problem to emphasise the relevance of the study objectives. Often, such remarks inadequately describe the magnitude of the problem, however, as in most cases the impact of heath problems on the quality of life of the patients is not based on validated measure- ment. For instance, in Lower Urinary Tract Symptoms (LUTS) suggestive of Benign Prostatic Obstruction (BPO), authors often refer to the high prevalence of the condition in older males, but the relative impact of LUTS suggestive of BPO on quality of life compared to other health problems is unknown. Quality of life instruments used in economic evalua- tion are especially suitable to estimate the impact of a condition on quality of life, because their outcome is the value or ``utility'' people attach to health states. * Corresponding author. Tel. 31-10-4088641; Fax: 31-10-4089094. E-mail address: mcdonnell@bmg.eur.nl (J. McDonnell). 0302-2838/02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0302-2838(02)00403-7