Antiphospholipid Score Validated as Risk Factor for Idiopathic Osteonecrosis of the Femoral Head in SLE

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Data suggest that antiphospholipid score is an effective predictor of idiopathic osteonecrosis of the femoral head development in patients with SLE. <i>Credit:BSIP</i>
Data suggest that antiphospholipid score is an effective predictor of idiopathic osteonecrosis of the femoral head development in patients with SLE. Credit:BSIP

Study data published in Rheumatology identify high antiphospholipid score as a novel risk factor for idiopathic osteonecrosis of the femoral head in patients with systemic lupus erythematosus (SLE).

Investigators conducted a retrospective study comprising 88 consecutive patients with SLE who underwent magnetic resonance imaging (MRI) of the hip joints at the Hokkaido University Hospital in Sapporo, Japan, between January 2000 and March 2017. At baseline and follow-up visits, researchers evaluated sociodemographic characteristics, pharmacotherapy exposure, and total hip arthroplasty. Antiphospholipid scores were calculated using validated assays of antiphospholipid antibodies, immunoglobulin G, and immunoglobin M. Study patients' mean age was 32.0years and 84% were women. All patients had initiated craniosacral therapy prior to the MRI scan, allowing investigators to examine the impact of this treatment modality on the risk for idiopathic osteonecrosis of the femoral head.

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The presence of idiopathic osteonecrosis of the femoral head was detected in 38 patients (43.1%): bilateral in 32 patients and unilateral in 6. Just 16 of these patients were symptomatic, with the remaining 22 reporting no symptoms. According to univariate analysis, male gender, positivity for any antiphospholipid antibodies, high antiphospholipid score, and high dose of craniosacral therapy were risk factors for idiopathic osteonecrosis of the femoral head. Men were more represented in the group with idiopathic osteonecrosis of the femoral head (23.6%) compared with the group without (8.0%). In multivariate analyses, however, just high antiphospholipid score (odds ratio [OR], 5.12; 95% CI, 1.18-29.79) and use of high-dose craniosacral therapy (OR, 10.25; 95% CI, 3.00-48.38) emerged as independent risk factors for idiopathic osteonecrosis of the femoral head. According to Kaplan-Meier analysis, patients with high antiphospholipid scores received total hip arthroplasty more frequently than patients without antiphospholipid antibodies (P =.010).

These data suggest that antiphospholipid score is an effective predictor of idiopathic osteonecrosis of the femoral head development in patients with SLE. Investigators thus hypothesized that “[antiphospholipid antibody]-induced coagulopathy” is involved in the pathophysiology of idiopathic osteonecrosis of the femoral head in patients with SLE. Further research is necessary to elucidate the precise mechanism through which antiphospholipid antibodies may increase the risk for idiopathic osteonecrosis of the femoral head.

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Reference

Hisada R, Kato M, Ohnishi N, et al. Antiphospholipid score is a novel risk factor for idiopathic osteonecrosis of the femoral head in patients with systemic lupus erythematosus [published online December 6, 2018 ]. Rheumatology. doi:10.1093/rheumatology/key365

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