Validation of a harmonized Spanish version of the IPSS: evidence of equivalence with the original American scale. International Prostate Symptom Score.

OBJECTIVES

To validate the use in Spain of a linguistically harmonized Spanish version of the International Prostate Symptom Score (IPSS Sp), and to compare it with the original American scale (IPSS Am).

METHODS

Validity and reliability were studied in 59 patients with benign prostatic hyperplasia (BPH) (age >50 years) and 68 control subjects without BPH (age 18 to 49 years). Construct validity was assessed by correlating IPSS Sp scores with the EuroQol-5D (EQ-5D), the Psychological General Well-Being Index (PGWBI), and item 8 (quality of life) of the IPSS. Discriminatory power was assessed by calculating the area under the receiver operating characteristic (ROC) curve. Reliability was evaluated using the test-retest method, and internal consistency was assessed using Cronbach's alpha. Sensitivity to change was expressed as the effect size in preintervention versus postintervention scores in 26 additional patients with BPH (age >50 years) who underwent transurethral resection of the prostate.

RESULTS

Correlations of the IPSS Sp were -0.07 to 0.36 with EQ dimensions; -0.29 with the EQ visual analogue scale score; 0.14 to 0.41 with PGWBI dimensions; and 0.72 with item 8 of the IPSS. ROC area was 0.95 +/- 0.02 (standard error). Using a cutoff point of 7, sensitivity was 83% and specificity was 98%. Test-retest reliability was 0.92 and Cronbach's alpha was 0.79. Mean preoperative and postoperative IPSS Sp scores were 25.56 and 8.48, respectively (P < 0.001 ). Overall effect size was 2.52. These results are similar to those of the original American scale.

CONCLUSIONS

This Spanish translation of the IPSS is valid, reliable, and sensitive to clinical change and has demonstrated equivalent psychometric properties to the original American instrument. Scores obtained with the two instruments can therefore be reliably compared and aggregated when statistically appropriate.