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

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; chi(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.