Simplified Chinese version of the international prostate symptom score and the benign prostatic hyperplasia impact index: cross-cultural adaptation, reliability, and validity for patients with benign prostatic hyperplasia

BACKGROUND: The aim of this study was to translate and cross-culturally adapt the international prostate symptom score (IPSS) and benign prostatic hyperplasia impact index (BII) into simplified Chinese for mainland Chinese patients with benign prostatic hyperplasia (BPH). METHODS: The original English IPSS and BII were translated into simplified Chinese versions based on cross-cultural adaptation guidelines. Internal consistency was evaluated with Cronbach’s α, then test-retest reliability with intraclass correlation coefficients (ICCs) in stable patients. The validity of these two adaptations was tested by the correlation between the IPSS and BII with visual prostate symptom score (VPSS) and 36 items Short Form Health Survey (SF-36). The floor and ceiling effects were calculated by the proportion of participants who obtained the highest and lowest possible score. RESULTS: A total of 105 native Chinese-speaking patients with BPH were enrolled. Cronbach’s α was over 0.75 for the simplified Chinese IPSS (IPSS 0.815; IPSS-symptom 0.782) and 0.709 for the simplified Chinese BII, indicating acceptable internal consistency. The ICCs for the test-retest reliability were over 0.75 (IPSS, r = 0.836; IPSS-symptom, r = 0.801; IPSS-quality of life, r = 0.794; BII, r = 0.758), indicating excellent test-retest reliability. There were very good positive correlations between IPSS and BII (r = 0.605), as well as VPSS (r = 0.634), and very good or good negative correlations between IPSS-Qol and SF-36 physical functioning (r = −0.621), and vitality (r = −0.659), and between BII and SF-36 physical functioning (r = −0.421). No floor or ceiling effect was detected in the simplified Chinese IPSS and BII. CONCLUSIONS: This study indicates that the simplified Chinese IPSS and BII are reliable and valid measurements of the symptom and quality of life among Chinese patients with BPH, which is likely to be widely used in this population.