Development of the Italian version of the Neuropathic Pain Questionnaire (NPQ): a reliability and validity study.

Abstract

To translate, culturally adapt, and assess the psychometric properties of the Italian version of the Neuropathic Pain Questionnaire (NPQ). The Italian version of the NPQ, developed following international guidelines, was administered with other measurement instruments to 110 subjects with neuropathic pain. Structural validity (exploratory factor analysis [EFA]), internal consistency (Cronbach's alpha), test-retest reliability (intraclass correlation coefficient [ICC]), measurement error (minimal detectable change [MDC]), and construct validity (hypothesis testing) were assessed. EFA reported an one-factor structure (ratio between the first and the second eigenvalue was equal to 3.286, and the variance accounted for by the first factor was equal to 38.9%, with eigenvalues explaining the 38.9% of the variance). Internal consistency was adequate (Cronbach's alpha = 0.84), and test-retest reliability (assessed in a subsample of 32 subjects) was excellent (ICC = 0.86; 95% CI: 0.74-0.93). The measurement error analysis revealed a MDC equal to 1.08 points (corresponding to 13.2% of the total score range). The construct validity was moderate, as 71.4% (five out of seven) <i>a-priori</i> hypotheses were met. The Italian version of the NPQ is available for clinical and research purposes, as its reliability and validity were met, and it can be used to assess neuropathic pain.