400. Clinical Characteristics of Patients With ANCA-associated Vasculitis in a Scandinavian Cohort

Background/Objectives: Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), two different ANCA-associated vasculitides (AAV), are characterized by necrotizing vasculitis affecting small blood vessels and the presence of autoantibodies, ANCAs. While the prevalence of AAV is roughly equal between males and females, few studies have investigated whether the clinical presentation of AAV differs between the sexes. Likewise, little is known about the presentation of AAV in patients diagnosed as young adults, in comparison with patients diagnosed with AAV later in life. With the intention to identify clinical tools to improve prediction of outcome in patients with AAV, the aim of this study was to investigate the impact of sex and age at diagnosis on clinical manifestations of GPA/MPA and ANCA specificity.

Methods: In a systematic multicenter study, 1165 patients with AAV attending the clinics of ten different Scandinavian rheumatological and/or nephrological centers, were consecutively enrolled. All patients were adults at the time of inclusion in the study and were classified into GPA or MPA according to the European Medicines Agency algorithm. Clinical data including sex, age, date of diagnosis, ANCA-specificity and any type of engagement of upper airways/ears, lungs, kidneys, eyes, gastrointestinal tract, heart, peripheral nervous system, central nervous system, skin or joints/muscles (ever) were collected from medical records. Disease manifestations were analyzed for associations with diagnosis (GPA/MPA), ANCA-specificity, age at diagnosis, sex and disease duration using simple and multiple logistic regression, with a P value threshold for significance of <0.05.

Results: Of 1165 AAV-patients, 916 had GPA (483 male/ 433 female) and 249 had MPA (98 male/ 151 female), with mean (SD) age at diagnosis of 51 (17.7) and 62 (14.9) for GPA and MPA, respectively. In the whole patient cohort, the age at diagnosis showed a bimodal pattern, with two peaks of incidence with median (range) at 22 (9-31) and 60 (32-91) years of age, respectively. Out of the 180 patients diagnosed before the age of 32, 166 had GPA (92 %); in this group, involvement of upper airways/ears, eyes and the gastrointestinal tract was significantly more common than in GPA patients diagnosed at an older age. Among all patients with GPA, a significantly larger proportion of females than males were younger than 32 years old at diagnosis (21% and 16%, respectively). Among all AAV patients, engagement of upper airways/ears, lungs, skin, eyes, the central nervous system and joints/muscles was significantly more common in GPA than MPA, whereas kidney involvement was significantly more common in MPA. In GPA, involvement of kidneys or lungs was significantly more common in males than in females and, additionally, there was a significantly higher rate of kidney failure in males. In MPA, engagement of upper airways/ears was significantly more common in females than in males. In both GPA and MPA, the presence of PR3-ANCA was significantly more common inmales than in females and MPO-ANCA was significantly more common in females than in males.

Conclusion: Our results indicate that GPA and MPA are characterized by different clinical manifestations and ANCA subtypes in males and females, with implications for prediction of prognosis and clinical decision-making. Moreover, a higher rate of females and increased frequency of upper airway/ear involvement in patients at younger age at diagnosis could suggest specific environmental triggers and pathogenic mechanisms in this subgroup of AAV patients.

Disclosures: None