medwireNews: The risk for flares during and after pregnancy is low and the severity typically mild in women who have inactive or stable systemic lupus erythematosus (SLE) in early pregnancy, show data from the PROMISSE study.
The findings, which appear in Arthritis Research & Therapy, are based on the prospective data for 619 women who had inactive or stable mild disease activity, with an average Systemic Lupus Erythematosus Pregnancy Disease Activity (SLEPDAI) score of 2.79 and Physician Global Assessment (PGA) score of 0.4, when they were recruited to the study at 8–12 weeks into their pregnancy.
During pregnancy, 20.8% of 384 women had a mild-to-moderate flare while 6.25% had a severe flare, according to the SELENA–SLEDAI flare index. This equated to respective incidence rates of 0.30 per person–year and 0.09 per person–year. The majority of flares occurred in the later stages of pregnancy, with only 4% occurring during the first trimester.
Similar rates and severity of flare were also seen for 234 women assessed 2–6 months postpartum, with 22.7% experiencing a mild-to-moderate flare at a rate of 0.8 per person–year and 1.7% experiencing a severe flare at a rate of 0.06 per person–year.
Most mild flares did not require any treatment and the study investigators describe the consequences of postpartum flares as “minimal.”
Only 19 of 57 postpartum flares were treated: 13 by an increase in prednisone dose; six with nonsteroidal anti-inflammatory drugs or hydroxychloroquine; and one with mycophenolate mofetil.
The researchers note that “even in patients with risk factors, rates of flares were low,” and propose that the most likely reason is because “PROMISSE patients had inactive or stable mild disease activity during the first trimester.”
The risk factors significantly and independently associated with an increased likelihood of having at least one flare during pregnancy in multivariable analysis included younger age and low complement component 4 (C4) and PGA score.
Indeed, the risk for flare decreased by 8% with every 1-year increase in age at baseline and increased by 48% with each 0.5 increase in PGA score, while patients with low C4 levels at baseline were 87% more likely to have a flare than those with normal levels.
After accounting for patients who had more than one flare in a negative binomial regression model, the researchers confirmed that younger age, higher PGA, and lower C4 persisted as the strongest independent predictors for a flare during pregnancy, although the association was only significant for the former two variables.
Yet, Jill Buyon (New York University School of Medicine, USA) and team say: “No predictors of flares post-partum were identified, including having had a flare during pregnancy.”
Buyon et al emphasize that “[b]ased on these results, physicians can reassure their patients that if they plan their pregnancy at a time of quiescence, they are unlikely to have a flare during or in the 6 months after pregnancy.”
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Arthritis Res Ther 2020; 22: 52