ASSOCIATION OF MICROHEMATURIA WITH OUTCOMES IN ADULT PATIENTS WITH IGA NEPHROPATHY

Abstract Background and Aims Although hematuria is the cardinal symptom of IgA nephropathy (IgAN), its effects on the outcome have not been studied extensively. We, therefore, aimed to analyze the association between microhematuria and clinicopathological features as well as outcome parameters in adult patients with IgAN. Method 129 adults with IgAN, diagnosed by kidney biopsy, and followed up for a median duration of 54.5 (IQR: 24.25-92.75) months, were included in this retrospective study. Urinary sediment analyses during the bouts of macrohematuria were not taken into consideration. For the purpose of this analysis, microhematuria was described as ≥5 red blood cells per high-power field (RBCs/hpf) and classified as mild (5-9 RBCs/hpf), moderate (10-19 RBCs/hpf), or severe (≥20 RBCs/hpf). Study outcome (event) was defined as at least a 50% reduction in baseline eGFR or development of stage 5 chronic kidney disease (eGFR <15 ml/min/1.73 m2). eGFRs of the patients were calculated by using CKD-EPI formula. Results Demographic, clinical, laboratory and histopathological features of patients at the time of diagnosis are summarized in the table. Usage of ACEi/ARBs [75/81 (92.5%) vs 45/48 (93.75%), p=0.803], fish oil [30/81 (37%) vs 19/48 (39.5%), p=0.773], azathioprine [16/81 (19.7%) vs 10/48 (20.8%), p=0.882] and mycophenolic acid derivatives [14/81 (17.2%) vs 11/48 (22.9%), p=0.434] were comparable among the patients with and without microhematuria. Corticosteroids were more frequently used in patients with microhematuria [41/81 (50.6%) vs 17/48 (35.4%)], although this difference was not statistically significant (p=0.093). Overall 30 patients (23.2%) reached the study outcome, and there were no differences between patients with (19, 23.4%) and without (11, 22.9%) microhematuria (p=0.944). Kaplan-Meier analysis revealed that event free survival rates were similar across study groups: 77.1% for patients without microhematuria; while 80% for mild, 77.3% for moderate, and 72.7% for severe microhematuria (p=0.436) (Figure). Microhematuria did not predict the study outcome when multivariable Cox regression analyses were performed [HR: 1.847 (95% CI: 0.696-4.904), p=0.218]. Throughout the follow-up, microhematuria disappeared (dropped below 5 RBCs/hpf) in 43 patients (53%), 8 of whom (18.6%) reached the study outcome as compared to 11 patients (28.9%) with persistent microhematuria (p=0.273). Disappearance of microhematuria was not a predictor of study outcome, as well [HR: 0.386 (95% CI: 0.068-2.180), p=0.281]. Conclusion Microhematuria is not associated with renal outcomes of adult patients with IgAN.