Clinical risk factors as predictors of postmenopausal osteoporosis in general practice.

Abstract

BACKGROUND: Case-finding strategies to identify women with high risk for osteoporotic fractures have recently been proposed, but little information about such an approach in general practice is known. AIM: To study the validity of the proposed case-finding strategy for osteoporosis. DESIGN OF STUDY: Survey using case-finding strategy. SETTING: Seven hundred and twelve women aged between 55 and 84 years, randomly selected from a general practice in The Netherlands. METHOD: Of the 712 randomly selected women, 449 women participated. Information was obtained from a questionnaire, direct questioning, and computerised patients files. Bone mineral density of the femoral neck was measured by dual energy X-ray absorptiometry and vertebral morphometry was performed on lateral X-rays of the spine. Osteoporosis was defined by a bone mineral density T-score of less than 2.5 and/or the presence of severe vertebral deformities. Sensitivity, specificity, and predictive values were calculated for the whole set of risk factors; those significantly associated with osteoporosis and in logistic models. RESULTS: Clinical risk factors were present in 55% of the women and identified 68% of the women with osteoporosis. Three risk factors--a low body mass index, fragility fractures, and severe kyphosis and/or loss of height--were associated significantly with osteoporosis; they were present in 33% of the women and identified 60% of those with osteoporosis. A logistic model based on age and fragility fractures selected 32% of the women and identified 76%. CONCLUSION: No single risk factor could assist in identifying women with osteoporosis. A simplified case-finding strategy using only three risk factors, that is suitable for primary care, reduces the number of women to be evaluated by two-thirds; however, this is at the cost of missing the diagnosis in 40% of the women with osteoporosis. Addition of spine radiographs to the case-finding approach helped to obtain a better risk profile of the women and had also practical consequences for the management of some. We propose that radiographs should be included in any case-finding strategy.