Development of a shorter version of the osteoporosis knowledge assessment tool

The aim of the authors of this study was to develop a short version of the Osteoporosis Knowledge Assessment Tool to be used for the target population of young adult Serbian females as an easily implemented add-on questionnaire. The 20-item Osteoporosis Knowledge Assessment Tool was translated and culturally adapted using the Principles of Good Practice for the Translation and Cultural Adaptation Process for Patient-Reported Outcomes Measures. The validation study was conducted on a sample of 250 female students studying at the Faculty of Pharmacy at the University of Belgrade, during a two-month period (November-December 2010). The difficulty index, item-total correlations, and internal consistency were calculated first. Afterward, confirmatory factor analysis was applied to test the structure of the Osteoporosis Knowledge Assessment Tool models and develop a short version. The mean total Osteoporosis Knowledge Assessment Tool score was 8.31 (possible range 0-20). The confirmatory factor analysis fit indices indicated poor fit of the data to the originally hypothesized structure. The confirmatory factor analysis fit indices, difficulty indices, and content validity allowed trimming of the original model and development of a short version with nine items. The average chi-square value for the Osteoporosis Knowledge Assessment Tool short version was 31.79 (p = 0.240, SE = 0.176) with Bollen-Stine bootstrap p = 0.249, Tucker-Lewis Index = 0.925, Comparative Fit Index = 0.944 and Root Mean Square Error of Approximation = 0.027. The Osteoporosis Knowledge Assessment Tool thus had acceptable characteristics and may be used for osteoporosis knowledge assessment.