The BILAG2004-Pregnancy Index is a valid disease activity outcome measure for pregnant SLE patients

Abstract

Objectives This study was to determine if the BILAG2004-Pregnancy Index (BILAG2004-P) has construct/criterion validity and is sensitive to change. Methods This was an observational multi-centre study which recruited pregnant SLE patients. Data was collected on disease activity (using BILAG2004-P and physician’s global assessment, PGA), investigations and therapy at each assessment. Overall BILAG2004-P score as determined by the highest score achieved by any system was used in the analysis. Cross sectional analysis was used for construct and criterion validity. The comparison was with C3, C4 and anti-dsDNA for construct validity whilst it was with change in therapy and PGA in criterion validity. Sensitivity to change was assessed by determining the relationship between change in BILAG2004-P and change in therapy between 2 consecutive visits. Results 97 patients with 112 pregnancies were recruited. There were 610 assessments available for construct/criterion validity analysis (98.2% pregnancies had more than 1 assessment) and 497 observations for sensitivity to change analysis. Increasing BILAG2004-P scores were associated with low C3. Active BILAG2004-P score (Grade A or B) was associated with increase in therapy and PGA of active disease. There was increasing likelihood of higher overall scores with increase in therapy and PGA of active disease. In the sensitivity to change analysis, increase in BILAG2004-P score was associated with increase in therapy and inversely associated with decrease in therapy. Decrease in BILAG2004-P score was associated with decrease in therapy and inversely associated with increase in therapy. Conclusion The BILAG2004-Pregnancy index has criterion validity and is sensitive to change. Lay Summary What does this mean for patients? Lupus is a chronic autoimmune disease that mainly affects women of child-bearing age. Thanks to improvements in lupus management, more women with lupus are able to become pregnant. However, changes during pregnancy can mimic some features of active lupus, which makes it more difficult to assess disease activity. Therefore, we have to adjust the way we assess lupus in pregnant patients. The BILAG2004-Pregnancy Index is a modified version of the BILAG-2004 index. While the BILAG-2004 Index is used to assess non-pregnant patients, the modified version should allow us to assess lupus activity in pregnant patients. This large study involved several medical centres and compared the BILAG2004-Pregnancy Index to other markers and an external standard reference. We found that the BILAG2004-Pregnancy Index appropriately measures lupus activity and is therefore a valid way to assess disease activity in pregnant patients. This finding will enable further research into lupus disease activity during pregnancy.

How can we accurately measure disease activity during pregnancy in systemic lupus erythematosus? New insights from the BILAG-2004 Pregnancy Index

“…It is paramount that treatment decisions in pregnancy rely on tools that provide accurate disease activity assessment. In the manuscript by Yee et al [ 4 ] presented in this edition of the journal, the authors sought to assess whether the BILAG2004-Pregnancy Index (BILAG2004-P), a modification of the commonly used BILAG-2004 Index, could sensitively detect changes in SLE disease activity across the duration of pregnancy over time.…”

“…The present study by Yee et al [ 4 ] assesses whether the BILAG-P is both valid and sensitive to change throughout pregnancy in a group of 97 patients (with a total of 112 pregnancies) recruited from five specialist lupus centres in England. The authors conducted an observational cross-sectional study to test whether BILAG-P had both construct validity (measured through standard laboratory measures of SLE disease activity, including complement C3 and C4 levels and anti-dsDNA antibody titres) and criterion validity (using the physician global assessment score) over the course of pregnancy.…”

Management of Rheumatic Diseases During Pregnancy and Breastfeeding

“…AGG RECOMMENDATION (26) Pregnant women with rheumatic disease should be actively asked about Raynaudʼs phenomenon of the nipple, informed, and treated if necessary.…”

“…Abnormal C-reactive protein, a high erythrocyte sedimentation rate, a differential blood cell count, urine analysis including the protein/creatinine ratio and anti-DNS, complement usage with decreasing levels of C3 or C4, transaminases and LDH may indicate a lupus flare, even in (still) asymptomatic patients. Lupus activity indices have now also been validated for pregnant women with lupus disease (including the LAI-P or BILAG2004 Pregnancy Index) 25 , 26 . The angiogenesis markers sFlt1/PlGF may be used as an indication of placental involvement to obtain a differential diagnosis of preeclampsia.…”

“…Auffälligkeiten im C-reaktiven Protein, der Blutsenkungsgeschwindigkeit, dem Differenzialblutbild, der Urinanalyse inklusive Protein/Kreatinin-Ratio sowie Anti-DNS, Komplementverbrauch mit sinkenden C3- oder C4-Werten, Transaminasen und LDH können einen Lupusschub auch bei der (noch) asymptomatischen Patientin anzeigen. Lupus-Aktivitäts-Indices wurden mittlerweile auch für an Lupus erkrankte Schwangere validiert (u. a. der LAI-P oder BILAG2004-Pregnancy Index 25 , 26 . Zur Differenzialdiagnose Präeklampsie kann mit den Angiogenesemarkern sFlt1/PlGF ein Hinweis auf eine plazentare Beteiligung gewonnen werden.…”