Stone, John H.

Summary Anti-neutrophil cytoplasmic antibodies (ANCA) appear to play an important role in the pathogenesis of ANCA-associated vasculitis (AAV). However, ANCA alone are not sufficient to generate disease, and some evidence suggests that infectious triggers may serve as inciting events for AAV disease activity. Antibodies of the immunoglobulin (Ig)M isotype often serve as markers of recent infection, and IgM ANCA have been identified previously in patients with AAV, although the frequency and clinical relevance of IgM ANCA is not well established. We sought to characterize IgM ANCA more clearly by creating a novel enzyme-linked immunosorbent assay (ELISA) for IgM antibodies to proteinase 3 [IgM proteinase 3 (PR3)–ANCA], which we applied to two large, clinically well-characterized trial cohorts of patients with granulomatosis with polyangiitis and microscopic polyangiitis. In the first cohort, IgM PR3–ANCA occurred with a frequency of 15·0%, and were associated with a higher degree of disease severity and a trend towards a higher rate of alveolar haemorrhage (29·6 versus 15·7%, P = 0·10). Analysis of follow-up samples in this cohort showed that the presence of IgM PR3–ANCA was transient, but could recur. In the second cohort, IgM PR3–ANCA occurred with a frequency of 41·1%, and were also associated with a higher degree of disease severity. A higher rate of alveolar haemorrhage was observed among those with IgM PR3–ANCA (45·3 versus 15·8%; P < 0·001). The association of transient IgM PR3–ANCA with an acute respiratory manifestation of AAV suggests a possible link between an infectious trigger and AAV disease activity.

ObjectiveWe investigated the relationships between glucocorticoid use, disease activity, and changes in body mass index (BMI) in patients with antineutrophil cytoplasmic antibody–associated vasculitis (AAV).MethodsWe analyzed AAV patients enrolled in the Rituximab in AAV trial. Glucocorticoid use, BMI, and disease activity were measured regularly during the trial period. We performed mixed‐effects regressions to examine the associations of time‐dependent cumulative average glucocorticoid use and disease activity with changes in BMI over time, while adjusting for potential confounders.ResultsThe mean ± SD baseline BMI of the 197 patients enrolled was 28.8 ± 6.3 kg/m2. Patients with newly diagnosed AAV tended to have a lower mean ± SD BMI than those with relapsing disease (28.0 ± 5.7 kg/m2 versus 29.6 ± 6.8 kg/m2) and higher disease activity (mean ± SD Birmingham Vasculitis Activity Score for Wegener's Granulomatosis 8.7 ± 3.3 versus 7.4 ± 2.7). The most significant change in BMI occurred during the first 6 months of the trial (mean ± SD increase of 1.1 ± 2.2 kg/m2; P < 0.0001). Disease activity improvement, glucocorticoid exposure, and randomization to rituximab were each independently associated with an increase in BMI (P < 0.001 for all analyses).ConclusionOur findings suggest that changes in BMI, as well as glucocorticoid exposure, are independently associated with improvements in disease activity in AAV. Rituximab may also have effects on BMI independent of its impact on disease activity.

ObjectiveTo 1) describe the distribution of patient global assessment (PtGA) scores of disease activity in patients with granulomatosis with polyangiitis (GPA; Wegener's), 2) explore the discordance between PtGA scores and physician global assessment (PhGA) scores of disease activity, and 3) explore whether PtGA scores during disease remission are associated with future disease relapse.MethodsData from the Wegener's Granulomatosis Etanercept Trial (WGET) were used. PtGA and PhGA scores were assessed on 100‐mm visual analog scales (VAS). Presence of active disease was determined using the Birmingham Vasculitis Activity Score for WG (BVAS/WG), and remission was defined as a BVAS/WG score of 0. Disease relapse was defined as a BVAS/WG score of >0 after remission had been achieved. Discordance between PtGA and PhGA scores was defined as a difference of ≥20 points between the two measures. Mixed linear models were used in longitudinal analysis of PtGA scores.ResultsData were obtained from 180 patients in the WGET cohort, seen at a total of 1,719 study visits. The mean ± SD PtGA and PhGA disease activity scores (on 100‐mm VAS) at baseline were 64.2 ± 27.4 and 55.5 ± 23.4, respectively. PtGA–PhGA discordance occurred in 53% of patients at baseline, and this was inversely associated with newly diagnosed disease (as opposed to relapsing disease) at baseline (odds ratio 0.37, 95% confidence interval [95% CI] 0.20–0.68) but not with age, sex, or presence of renal or pulmonary disease. Patients were in disease remission during 62% of the study visits. The mean PtGA score during visits immediately prior to relapse was 4.52 points higher (95% CI 0.66–8.4) than that at other remission visits (P = 0.03).ConclusionPtGA–PhGA discordance is common in GPA. A rise in the PtGA disease activity score during times defined by physicians as periods of remission is associated with subsequent occurrence of disease relapse. These findings support the addition of PtGA as an outcome measure for GPA.