Classification of Osteoporosis Based on Bone Mineral Densities

Abstract

In this article we examine the role of bone mineral density (BMD) in the diagnosis of osteoporosis. Using information from 7671 women in the Study of Osteoporotic Fractures (SOF) with BMD measurements at the proximal femur, lumbar spine, forearm, and calcaneus, we examine three models with differing criteria for the diagnosis of osteoporosis. Model 1 is based on the World Health Organization (WHO) criteria using a T score of ؊2.5 relative to the manufacturers' young normative data aged 20 -29 years, with modifications using information from the Third National Health and Nutrition Examination Survey (NHANES). Model 2 uses a T score of ؊1 relative to women aged 65 years at the baseline of the SOF population. Model 3 classifies women as osteoporotic if their estimated osteoporotic fracture risk (spine and/or hip) based on age and BMD is above 14.6%. We compare the agreement in osteoporosis classification according to the different BMD measurements for the three models. We also consider whether reporting additional BMD parameters at the femur or forearm improves risk assessment for osteoporotic fractures. We observe that using the WHO criteria with the manufacturers' normative data results in very inconsistent diagnoses. Only 25% of subjects are consistently diagnosed by all of the eight BMD variables. Such inconsistency is reduced by using a common elderly normative population as in model 2, in which case 50% of the subjects are consistently diagnosed as osteoporotic by all of the eight diagnostic methods. Risk-based diagnostic criteria as in model 3 improve consistency substantially to 68%. Combining the results of BMD assessments at more than one region of interest (ROI) from a single scan significantly increases prediction of hip and/or spine fracture risk and elevates the relative risk with increasing number of low BMD subregions. We conclude that standardization of normative data, perhaps referenced to an older population, may be necessary when applying T scores as diagnostic criteria in patient management. A risk-based osteoporosis classification does not depend on the manufacturers' reference data and may be more consistent and efficient for patient diagnosis.

Differences in Site-Specific Fracture Risk Among Older Women with Discordant Results for Osteoporosis at Hip and Spine: Study of Osteoporotic Fractures

“…(20,20,21) Also in accord with earlier studies, our results show that an increase in the number of osteoporotic sites predicts a higher risk of incident fractures. (21,22,20) For example, in one large clinical referral population, the age-adjusted risk of any osteoporotic fracture ascertained from administrative records increased as the number of osteoporotic sites (total hip, femoral neck, trochanter, or lumbar spine) increased. (20) This association was eliminated by adjustment for total hip BMD as a continuous risk factor.…”

Age-related prevalence of osteoporosis and fragility fractures: real-world data from an Austrian Menopause and Osteoporosis Clinic

“…BMD measurements are commonly done by central DXA of the spine and hip. Peripheral BMD measurements with non-DXA techniques at the heel, forearm or hand are performed less commonly and their results correlate only poorly with central DXA 19 . The power of BMD to predict fracture risk at different sites, however, is improved by site-specific measurements, and hip or spine BMD predict forearm fracture risk less well than peripheral BMD 20,21 .…”

Comparison of Central and Peripheral Bone Mineral Density Measurements in Postmenopausal Women

“…It was reported that lack of agreement between central and peripheral DEXA is a barrier to recommending peripheral DEXA scan methods. 28,29 In the same context, Wigderowitz et al 30 examined the extent to which patients with Colles' fractures have osteopenia. They measured BMD in the contralateral radius of 235 women ranging from 21 to 92 years in age presenting with Colles' fractures over a 2-year period.…”