Cross-cultural adaptation and psychometric validation of the Spanish version of the Nasal Polyposis Quality of Life Questionnaire (NPQ).

INTRODUCTION

To perform the cross-cultural adaptation into Spanish and the psychometric validation of the Nasal Polyposis Quality of Life Questionnaire (NPQ) for use in patients with chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

A total of 140 adult patients diagnosed with CRSwNP were included. The original NPQ was adapted from Italian into Spanish following established international guidelines. Construct validity was assessed through exploratory factor analysis (EFA) with principal components. Internal consistency was analyzed using Cronbach's alpha coefficient. Test-retest reliability was determined by the intraclass correlation coefficient (ICC). Concurrent validity was examined using Pearson correlations with the SNOT-22 and NOSE-E questionnaires. Discriminant validity was analyzed using ROC curves.

RESULTS

EFA revealed a five-factor structure explaining 67% of the total variance. The Spanish NPQ showed excellent internal consistency (Cronbach's α = 0.917) and high test-retest reliability (ICC = 0.991; 95% CI: 0.983-0.996). The standard error of measurement (SEM) was 2 points, and the minimal detectable change (MDC95) was 5 points. Strong correlations were observed with the NOSE-E (r = 0.802) and SNOT-22 (r = 0.870). The NPQ total score demonstrated high discriminative ability for severe symptoms (AUC = 0.947), with a cutoff point >41 providing 88.9% sensitivity and 93.3% specificity.

CONCLUSIONS

The Spanish version of the NPQ is a valid, reliable, and clinically useful instrument for assessing symptom burden in patients with CRSwNP. Its multidimensional structure allows capturing the specific impact of this phenotype and supports its use in both clinical practice and research.