OBJECTIVE: Disease-specific questionnaires have often been used to reflect the gradation of specific disorders. However, disease-specific questionnaires do not allow appraisal of clinical outcomes within economic evaluations. Here, a solution could be to determine retrospective quality of life-weights for health states of disease specific questionnaires that previously have been used in trials. The main problem will be to reduce the large number of health states. We applied this method in the study of the quality of life effects of Benign Prostatic Hyperplasia (BPH). METHODS: Outcomes of BPH are measured using the IPSS, which health states can be converted into quality of life values using time trade-off. For that, a factor analysis and a decrease of answer levels are needed to reduce the number of health states to be valued. RESULTS: After factor analysis two main factors remain, namely “obstructive” (alpha = 0.8018) and “irritative” (alpha = 0.7165). Each of these factors identified by factor analysis was described at three levels in order to restrict the number of possible health states. The resulting 9 health states were valued by the general public. The quality of life values range from 0.8330 for the worst BPH-state to 0.9599 for the best BPH-state. The domain irritative appeared to be experienced as more “severe” than the domain obstructive. CONCLUSION: The study shows that by using a factor analysis the large number of health states can be reduced, which offers the possibility to convert disease-specific outcomes into utilities. The study also shows that the two different domains of BPH (obstructive and irritative) have a different impact on the quality of life values. Because the IPSS is now validated for the use in economic appraisal, new and already published research can be used to determine the cost per QALY of different interventions in BPH. RESPIRATORY DISORDERS