Development and validation of osteoporosis prescreening model for Iranian postmenopausal women

BACKGROUND Studies have indicated that the commonly used osteoporosis prescreening tools are not appropriate for use in every nation. This study was designed to develop and validate a prescreening model for bone mineral densitometry among Iranian postmenopausal women. METHODS From 13613 individuals who were referred for bone mineral densitometry in Shariati hospital in Tehran, 8644 postmenopausal women were considered for the study after excluding men and premenopausal women. Questionnaires regarding the risk factors for osteoporosis were filled for each individual. Bone mineral density at the lumbar vertebrae (L2-L4), femoral neck and total femur was measured by dual X-ray absorptiometry. Using holdout validation, the study sample was divided into two parts; training set (5705) and test set (2939). Logistic regression analysis was performed on the training set. A scoring model was developed and tested in the test set. RESULTS Based on the training set, a seven-variable model named OPMIP (Osteoporosis Prescreening Model for Iranian Postmenopausal women) was developed with C statistics (area under curve) of 0.72. Using a cut-off of -2.5 for the model, the sensitivity, specificity, positive predictive value and negative predictive value were 72%, 59.5%, 64% and 69% respectively. The model performance was tested in the test set. OPMIP correctly classified 67.10% of cases with a sensitivity and specificity of 73.2% and 61%. CONCLUSIONS In order to appropriately refer patients for a bone mineral densitometry, OPMIP can be used as a prescreening tool in Iranian Postmenopausal women.