after completion of the primary vaccination series (two doses of Pfzer or AstraZeneca vaccines) and 15–30 days after the third booster dose (Pfzer, given 3–6 months after the second dose). RESULTS: We included 20 patients with vasculitis [AAV, n = 16 (80%), IgAV, n = 4 (20%)] and renal involvement. All patients received immunosuppressives, including RTX (80%), MMF/AZA (15%), cyclophosphamide (5%), while half of patients were on glucocorticoids. The seroconversion rate after the primary two doses (Pfzer n = 8/16, Astra-Zeneca n = 1/1) was 53%, which increased to 67% after the third booster dose (Pfzer, n = 12/18). Similarly, the median antibody titers increased from 451 U/mL [interquartile range (IQR) 81–10.845] after the second dose to 1016 U/mL (ΙQR: 64– 37.568) after the booster dose. Regarding patients treated with RTX, the respective response rates after the second and third dose were 58% and 62%. Seropositive patients after the third dose tended to have lower previous cumulative exposure to RTX compared with seronegative ones (4.55 versus 5.5 g, P = .62, respectively). No vaccine side efects or disease relapses were noted after the three vaccine doses. CONCLUSION: In our patient cohort with systemic vasculitis and renal involvement treated mainly with RTX, a third booster vaccine dose increased the seropositivity rate from 53% to 67%. Nevertheless, one-third of patients did not achieve seroconversion. Whether a fourth booster dose could beneft these patients is still unknown. MO225 A PAST MEDICAL HISTORY OF AUTOIMMUNE DISEASE PREDICTS A FUTURE WITH FEWER RELAPSES IN PATIENTS WITH ANCA VASCULITIS Sophia Lionaki 1,2 , Smaragdi Marinaki 1,3 , Sofia Fragkioudaki 4 , Ioannis Bellos 4 , Emmanuel Kalaitzakis 4 , Petros Kalogeropoulos 4 , Angeliki Sardeli 2 , George Liapis 5 and Ioannis Boletis 1,3 1 National and Kapodistrian University of Athens, Athens, Greece, 2 Nephrology, Attikon University Hospital, Chaidari, Greece, 3 Nephrology, Laiko Hospital, Athina, Greece, 4 Laiko Hospital, Athina, Greece, 5 Pathology, Laiko Hospital, Athina, Greece BACKGROUND AND AIMS: To explore the frequency and impact of an autoimmune disease past-medical history (PMH) in the clinical picture and outcomes of patients with ANCA-associated vasculitis (AAV). METHOD: This is a retrospective study of patients with biopsy-proven AAV, >16 years old, with detailed information about their PMH. Outcomes of interest included remission, treatment resistance, relapse, end-stage kidney disease (ESKD), and death. RESULTS: 215 patients with biopsy-proven AAV and available information regarding their PMH were studied. A total of 65 (30.2%) of them had a history of autoimmune disease prior to PIV diagnosis. The mean age overall was 53.9 years. One hundred and fve patients (48.8%) were positive for PR3-ANCA, 101(47.2%) for MPO-ANCA, and 9(4.2%) were negative ANCA. Granulomatosis with polyangiitis was diagnosed in 79 (36.7%), microscopic polyangiitis in 101(47.0%) and renal-limited vasculitis in 35 (16.3%) individuals. Remission rate was similar among patients with and without a PMH of autoimmune disease. Time-to-event analysis indicated that the relapse-free survival was signifcantly longer in patients with PMH of autoimmune disease (148.2 versus 52.8 months, P-value < .001). After adjusting for covariates, autoimmune disease history was associated with signifcantly lower risk of relapse {HR 0.31, [95% confdence interval (CI) 0.14–0.69]}, which remained signifcant in males, patients ≥ 60 years old and those with C/PR3-ANCA, kidney and lung involvement. CONCLUSION: Patients with a PMH of autoimmune disease, prior to AAV diagnosis, experienced signifcantly fewer relapses after achievement of remission, compared with patients without such a history, underlining the importance of individualization of maintenance immunosuppressive therapy, given the diferent etiopathogenetic settings the disease was developed. MO226 IS REMISSION OF HEMATURIA ASSOCIATED WITH KIDNEY OUTCOME IN BIOPSY-PROVEN PRIMARY IGA NEPHROPATHY? Otilia Popa 1 , Gabriel Stefan 1,2 , Nicoleta Petre 3 , Daniela Dumitru 4 , Cristina-Stela Capusa 1,2 and Gabriel Mircescu 1,2 1 Nephrology and Internal Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania, 2 Nephrology, ‘Dr Carol Davila’ Teaching Hospital of Nephrology, Bucharest, Romania, 3 Nephropatology, ‘Dr Carol Davila’ Teaching Hospital of Nephrology, Bucharest, Romania and 4 Biochemistry laboratory, ‘Dr Carol Davila’ Teaching Hospital of Nephrology, Bucharest, Romania BACKGROUND AND AIMS: Microscopic hematuria, associated with variable proteinuria, is the most common clinical feature of IgA nephropathy (IgAN). However, its role in the disease progression is still controversial. This study aims to assess whether remission of hematuria is associated with kidney outcome in adults with primary IgAN. METHOD: This retrospective, longitudinal study enrolled 62 adults, out of 214 with biopsy-proven IgAN between 1 January 2008 and 31 December 2017 {age 41 [95% confdence interval (CI) 37–46] years, 73% males, eGFR 41.3 (95% CI 33.1–51) mL/min and proteinuria 1.1 (95% CI 0.9–1.6) g/g} who had at least three assessment visits 3 months apart until 31 May 2018. The median follow-up period was 68 (95% CI 58.6–77.3) months. Demographic (age, gender), comorbidities, clinical and laboratory data (proteinuria, hematuria and blood pressure) at the time of kidney biopsy and during the follow- up period were retrieved from medical records. Information about therapy was also recorded. The study endpoint was kidney death defned as doubling of serum creatinine or renal replacement therapy (RRT) initiation. Kidney survival was evaluated by Kaplan–Meier method and variables related to kidney outcome by multivariate Cox proportional hazard modeling. Remission of hematuria was defned as ≤ 5 red blood cells/high power feld in at least two samples taken no less than 3 months apart. Subjects were grouped as remission of hematuria (n = 24) and persistent hematuria (n = 38). RESULTS: There were no diferences between the two groups regarding demographic characteristics, comorbidities, kidney function, proteinuria, hematuria or infammation markers at time of kidney biopsy. During the follow-up period, remission of proteinuria (defned as a > 50% decrease in urinary protein-to-creatinine ratio from baseline) was found in more than half of the group with remission of hematuria but in less than a quarter of group with persistent hematuria (57.1% versus 24.2%; P = .02). However, systolic blood pressure was well controlled (<130 mmHg) in similar proportions (63.6 versus 57.9%, P = .7) and a comparable reduction in mean arterial blood pressure from the baseline was observed [MAP -7.8 (95% confdence interval (CI) -14.1 to -0.45) versus -2.8 (95% CI -9.7–4.9) mmHg; P = .2] in both groups. A high proportion of patients were treated with renin–angiotensin inhibitors (71 versus 61%; P = .5) and almost a third received immunosuppressive therapy (38 versus 34%; P = .8), similarly in the two groups. During the follow-up, a lower proportion of patients with remission of hematuria reached the composite kidney endpoint (16.7 versus 42.1%, P = .03). In the univariate time-dependent analysis, the kidney survival was numerically better in patients with remission of hematuria [(71.4 (95% CI 64.5–78.2) versus 66.02 (95% CI 54.7–77.2) months; log rank P = .06; Fig. 1A]. Abstract i153 Downloaded from https://academic.oup.com/ndt/article/37/Supplement_3/gfac067.025/6578440 by guest on 29 May 2023