Poor-fit indexes of Kupperman index: A psychometric analysis based on item response theory

Abstract

© 2014 by The North American Menopause Society. Objective This study aims to test the construct validity of the 11 items of the Kupperman index (KI), which has been pioneering in its attempt to quantify climacteric symptoms. Methods Unidimensional confirmatory factor analysis of the 11 graded items (hot flashes, paresthesia, insomnia, nervousness, melancholia, vertigo, weakness, arthralgia or myalgia, headache, palpitations, and formication), using a four-point scale (0, none; 4, severe), was used to evaluate the KI in a sample consisting of 84 women with a mean (SD) age of 54.34 (4.00) years who have been in menopause for a mean (SD) of 4.36 (2.53) years. Results The KI returned poor results on unidimensional model testing (root-mean-square error adjustment, 0.109; 90% CI, 0.075-0.142; comparative fit index, 0.871; Tucker Lewis index, 0.838; weighted root-mean-square residual, 0.971; χ 2 44 = 87.599; P < 0.001), indicating that the set of items does not properly evaluate the underlying phenomena (climacteric symptoms). Conclusions Our study verifies the poor fit of the KI and provides psychometric evidence that KI items warrant revision and/or that the concept underlying climacteric symptoms should be revisited.