medwireNews: A quarter of patients in remission for systemic lupus erythematosus (SLE) have elevated serum interferon (IFN)-α levels and may be at increased risk for relapse, French researchers report.
Writing in the Annals of the Rheumatic Diseases, Alexis Mathian (Pitié-Salpêtrière Hospital, Paris) and colleagues suggest that elevated serum IFN-α levels may therefore “constitute an independent predictive biomarker of lupus flares.”
Among 254 patients in SLE remission, according to the Definition of Remission in SLE classification, 26% had a baseline IFN-α level above the cutoff of 136 fg/mL when measured using an ultrasensitive single-molecule array digital immunoassay, which the researchers say “enables the measurement of cytokines at physiological concentrations.”
Patients in “clinical remission on treatment” had the highest median level of IFN-α, at 109 fg/mL, whereas those in “complete remission off treatment" had the lowest level, at 11 fg/mL, with the difference between the two groups statistically significant.
In multivariable analysis, having a positive Farr test, and being positive for anti-Ro/SSA 52 antibodies and anti-Ro/SSA 60 antibodies were all significantly associated with an increased likelihood of having a raised IFN-α level, at odds ratios (OR) of 2.3, 4.6, and 2.6, respectively.
By contrast, older age (OR=0.96) and lower granulocyte counts (OR=0.70) were associated with a lower likelihood of having elevated IFN-α.
During 1 year of follow-up, 9.6% of patients experienced an SLE flare, defined according to the SELENA-SLEDA index, just over a third (37.5%) of whom were severely affected.
Mathian and co-authors report that individuals with abnormal IFN-α levels at baseline were a significant four times more likely to experience a flare than those with normal IFN-α levels.
Furthermore, the area under the receiver operating characteristic curve for flare prediction with IFN-α was 0.73, whereas those for anti-double-stranded DNA antibodies and serum C3 levels were nonsignificantly lower, at 0.60 and 0.56, respectively.
Mathian et al therefore conclude: “Including serum IFN-α measurements in the routine laboratory assessments in patients in remission could help clinicians to identify a subgroup of SLE patients clinically in remission but who still overexpress IFN-α and are at higher risk of relapse.”
They add: “These data suggest that the return of normalcy of serum IFN-α could become one of the objectives of the treatment.”
By Laura Cowen
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Ann Rheum Dis 2019; doi:10.1136/annrheumdis-2019-215571