Background/Purpose: RA is in independent risk factor for osteoporosis and fractures. The diagnosis of osteoporosis is based on T-score at lumbar spine or hip and conventionally femoral BMD is measured at left hip. RA could affect hip BMD results as a consequence of impaired mobility and gait abnormalities related to the disease itself. Since treatment decision in patient with RA is frequently based on the FRAX tool score and it relies on hip BMD results, measuring the left hip only we could miss some patient with low BMD worth to be started on treatment.

Our aim was to assess if measuring BMD at both hips could increase the number of RA patients diagnosed with osteoporosis/osteopenia and potentially to be started on treatment.

Methods: RA patients who underwent a DXA scan at Royal Lancaster Infirmary between June 2006 and October 2015, and had both hips scanned were included in our analysis. We compared the prevalence of osteoporosis/osteopenia pending on the results of each hip using simple statistics.

Results: 1527 patients were included in our analysis. 1207 (79%) were female, mean age was 64.3 (SD 11.6), BMD levels (neck and total hip) were 0.85 g/cm2 (SD 0.15) and 0.90 g/cm2 (SD 0.17 ) at the left hip and 0.85 g/cm2 (SD 0.15) and 0.90 (SD 0.17) at the right hip.

According to left hip results (Neck or Total Hip) 198 patients (13%) were classified as osteoporotic and 621 (40.1%) as osteopenic, while according to right hip results 183 patients (12%) were classified as osteoporotic and 598 (39.2%) as osteopenic.

Overall 245/1527 (16%) patients could be diagnosed as osteoporotic with 136/245 patients having BMD levels in the osteoporotic range at both hips (55.5%), 62/245 patients (25.3%) at the left hip only and 47/245 patients (19.2%) at right hip only. No significant differences in terms of age, sex, BMI and steroid exposure were found among patients with discordant results between the two hips. Surprisingly a higher frequency of previous fragility fractures was observed in the group with osteoporosis at the right hip only compared to the one with osteoporosis at the left hip only (28/47 vs 23/62, p = 0.020).

Conclusion: Measuring BMD at both hips could increase the number of RA patients diagnosed with osteoporosis or osteopenia and consequently the number of patients started on bone sparing treatments. This strategy could eventually lead to a decrease of fragility fractures among patients with RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/bilateral-femoral-dxa-scan-in-patients-with-rheumatoid-arthritis/