Development and Internal Validation of the Vajira Osteoporosis Risk Score Index (VORSI) for Postmenopausal Osteoporosis Screening

Abstract

Objective: To develop and validate the Vajira Osteoporosis Risk Score Index (VORSI) to identify postmenopausal at risk of having osteoporosis.

Methods: The data was retrospectively collected from the medical records of 973 menopausal women attending menopause clinic at Faculty of Medicine, Vajira Hospital between January 2002 and January 2008. Data on age, body weight, menopausal duration, current estrogen use, previous low impact fracture, and lumbar and total hip bone mineral density (BMD) measurement by dual energy X-ray absorptiometry (DEXA) were collected. The subjects were randomized to either a development (n=386) or validation (n=587) cohorts. Data from the development cohort were used to develop a best fitting multivariable logistic regression model which was transformed into a simplified scoring algorithm, VORSI. Diagnostic performance of VORSI to identify osteoporosis in comparing with standard DEXA was determined in validation cohort.

Results: In development cohort, VORSI based on 3 variables of age (in year; <50=0, 50-59=1, 60-69=2, >70=3), body weight (in kilogram; >60=0, 50-59=1, <50=2), and current estrogen use (yes=0 no=2) showed a good discriminatory performance in identifying risk of osteoporosis in menopausal women. A score of 4 or greater yielded an area under the curve of (AUC) of 0.75 with the overall sensitivity of 71.9 %, and specificity of 62.1%. In validation cohort, VORSI at cut off > 4 also showed a good predictive validity with AUC of 0.78, sensitivity of 79.6 %, and specificity of 56.0%.   Using three categories according to probability of having osteoporosis, BMD measurements can be postponed in the category at lowest risk (VORSI < 4) and in the category at highest risk which treatment should be recommended (VORSI >5). BMD measurements are only necessary for those with index 4 to 5. This application can reduce unnecessary BMD measurements by 54.4 %.

Conclusion: VORSI is simple and effective approach to identify postmenopausal women at risk for osteoporosis in this study. Individuals with VORSI of 4 to 5 should be targeted for confirmatory DEXA scans.

Keywords: menopause, osteoporosis screening, bone mineral density