Comment on the article by Clowse, et al.
Clowse et al. report that ferritin, oestradiol, and uric acid level at mid-gestation may predict preterm delivery in systemic lupus erythematosus (SLE) with mild-moderate disease activity. This is a well- done study, but we believe that the authors fail to fully address the effect of antiphospholipid antibodies. The author states that four patients tested positive for antiphospholipid antibodies. However, the details of which specific antiphospholipid antibodies and total number of patients tested for antiphospholipid antibody were not mentioned in this article. A previous prospective study demonstrated that lupus anticoagulant was the strongest predictor of adverse pregnancy outcomes in patients with SLE. In addition, considering a previous study which reported that approximately 40% of SLE patients have antiphospholipid antibodies, the number of patients testing positive for antiphospholipid antibodies is relatively low in the study by Megan et al. We suspect that there may be a measure of selection bias, or alternatively, a portion of patients who in whom antiphospholipid testing was not performed. As the study included patients with unclear antiphospholipid antibodies profiles and substantially lower rates of antiphospholipid antibody positivity, it is uncertain whether their results are widely generalizable.
1. Clowse MEB, Wallace DJ, Weisman M, et al. Predictors of preterm birth in patients with mild systemic lupus erythematosus. doi: 10.1136/annrheumdis-2012-202449.
2. Lockshin MD, Kim M, Laskin CA, et al. Prediction of adverse pregnancy outcome by the presence of lupus anticoagulant, but not anticardiolipin antibody, in patients with antiphospholipid antibodies. Arthritis Rheum 2012;64(7):2311-2318.
3. Ruiz-Irastorza G, Crowther M, Branch W, Khamashta MA. Antiphospholipid syndrome. Lancet 2010;376:1498-1509.
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