Purpose: The prominence of health related quality of life end points in international clinical research underscores the importance of well validated and translated measures to enable cross-cultural comparison. The National Institutes of Health (NIH)-Chronic Prostatitis Symptom Index (CPSI) assesses symptoms and health related quality of life in men with chronic nonbacterial, NIH type III prostatitis. To expand its use to Spanish speaking patients we performed a translation and linguistic validation.
Materials and methods: The 9-item NIH-CPSI was translated into Spanish according to a standard methodology of 2 forward translations, 1 reconciled version, back translation of the reconciled version and 3 independent reviews by bilingual experts. The purpose of this methodology was to create a single universal Spanish version that would be acceptable to native Spanish speakers inside and outside of the United States. After the translation process the Spanish version was pre-tested in Argentina, Mexico, Spain and the United States. Patient responses were analyzed to identify necessary modifications. The internal consistency of the CPSI was evaluated using Cronbach's alpha. Pearson's product moment correlations were used to evaluate construct validity.
Results: Data were collected from chronic prostatitis patients, including 15 in Argentina, 15 in Mexico, 4 in the United States and 3 in Spain. The translation had high reliability overall and in all subscales (Cronbach's coefficient alpha = 0.81 to 0.94), and the subscales correlated well with each other (r = 0.76 to 0.97). However, patients expressed difficulty in distinguishing the response categories "a menudo" ("often") from "normalmente" ("usually") in question 3. We revised "a menudo" to "muchas veces" ("much of the time") and "normalmente" to "casi siempre" ("almost always") to improve the distinctiveness of response categories.
Conclusions: The Spanish NIH-CPSI has high reliability as well as face and construct validity in Spanish speaking men from various countries. The Spanish NIH-CPSI permits cross-cultural comparisons of men with chronic nonbacterial prostatitis.