Linguistic adaptation and validation of the Spanish version of the Benign Prostatic Hyperplasia-Patient Impact Measure (BPH-PIM)

Abstract

Background: The Benign Prostatic Hyperplasia-Patient Impact Measure (BPH-PIM) is a self-reported quality-of-life questionnaire for measuring the impact of urinary/prostate symptoms on the quality of life of patients with BPH. The aim of the present study was to adapt the original instrument to Spanish (for use in Spain) and to assess the psychometric properties of the new version.

Methods: Linguistic adaptation was performed using the standard processes for establishing conceptual equivalence, and was partially conducted in parallel with original instrument development. Psychometric properties were assessed on a sample of 131 patients with BPH who were receiving treatment with doxazosin gastrointestinal therapeutic system (GITS).

Results: All the standardised items had response rates > 99%; there were no floor or ceiling effects. Reliability in terms of Cronbach's alpha was 0.96 and the intraclass correlation coefficient was 0.97. Construct validity was confirmed by factor analysis. Convergent validity was confirmed in terms of the relationship to the 12-Item Short-Form Health Survey (SF-12) [p < 0.001], Health Utilities Index Mark III (HUI-3) [p < 0.001] and the International Prostate Symptom Score (IPSS) QOL item (p < 0.001). The instrument showed discriminant validity, in terms of IPSS groups (p < 0.001). The instrument was sensitive to change in terms of the correlation of the domain scores of the PIM to improvements in symptom scores (p < 0.001). Significant differences were observed for those who improved > or = 3 points in the IPSS scale (p < 0.001).

Conclusion: A psychometrically valid and conceptually equivalent version of the BPH-PIM questionnaire has been produced in Spanish to be used in Spain in patients with BPH.