Time-Varying Proteinuria and Progression of IgA Nephropathy: A Cohort Study.

RATIONALE & OBJECTIVE: Proteinuria is a surrogate end point for predicting long-term kidney outcomes in IgA nephropathy (IgAN) with levels<1g/day identified as a therapeutic target. However, this threshold has not been sufficiently studied. We quantified the associations of progression of IgAN with various levels of proteinuria. STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: 1,530 patients with IgAN and at least 12 months of follow-up at Peking University First Hospital. EXPOSURE: Proteinuria levels updated over time (time-varying proteinuria, TVP). OUTCOME: A composite kidney outcome of a 50% reduction in the estimated glomerular filtration rate or end-stage kidney disease. ANALYTICAL APPROACH: Marginal structural models. RESULTS: After a median follow-up period of 43.5 (IQR, 27.2-72.8) months, 254 patients (16.6%) developed the composite kidney outcome. A graded association was observed between TVP and composite kidney outcomes with higher risk among those with proteinuria of≥0.5g/day. Compared with TVP<0.3g/day, the HRs for proteinuria levels of 0.3 to<0.5g/day, 0.5 to<1.0g/day, 1.0 to<2.0g/day, and≥2.0g/day were 2.22 (95% CI, 0.88-5.58), 4.04 (95% CI, 1.93-8.46), 8.46 (95% CI, 3.80-18.83), and 38.00 (95% CI, 17.62-81.95), respectively. The trend was more pronounced in patients with baseline proteinuria of≥1.0g/day, among whom a higher risk was observed with TVP of 0.3 to<0.5g/day compared with TVP<0.3g/day (HR, 3.26 [95% CI, 1.07-9.92], P=0.04). However, in patients with baseline proteinuria levels of<1g/day, the risk of composite kidney outcome only began to increase when TVP was≥1.0g/day (HR, 3.25 [95% CI, 1.06-9.90]). LIMITATIONS: Single-center observational study, selection bias, and unmeasured confounders. CONCLUSIONS: This study showed that patients with IgAN and proteinuria levels of>0.5g/day, have an elevated risk of kidney failure especially among patients with proteinuria levels≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN. PLAIN-LANGUAGE SUMMARY: The presence of proteinuria has often been considered a surrogate end point and a possible therapeutic target in clinical trials in IgA nephropathy (IgAN). Some guidelines recommend a reduction in proteinuria to<1g/day as a treatment goal based on the results of previous longitudinal studies. However, these findings may have been biased because they did not properly adjust for time-dependent confounders. Using marginal structural models to appropriately account for these confounding influences, we observed that patients with IgAN and proteinuria levels≥0.5g/day have an elevated risk of kidney failure, especially among patients who had proteinuria levels of≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN.

Intensive blood pressure control and the progression of IgA nephropathy: a cohort study using marginal structural models.

BACKGROUND: In chronic kidney disease, current guidelines recommend systolic blood pressure (SBP) below 120 mmHg. However, the renoprotective effect of intensive blood-pressure (BP) lowering on immunoglobulin A nephropathy (IgAN) remains undetermined. We aimed to determine the effect of intensive BP control on the progression of IgAN. METHODS: At Peking University First Hospital, 1530 patients with IgAN were enrolled. An examination of the relationship between baseline and time-updated BP and composite kidney outcomes, defined as development of end-stage kidney disease (ESKD) or a 30% decline in estimated glomerular filtration rate (eGFR), was conducted. Baseline and time-updated BPs were modeled using multivariate causal hazards models and marginal structural models (MSMs). RESULTS: In a median follow-up of 43.5 (interquartile range 27.2, 72.7) months, 367 (24.0%) patients experienced the composite kidney outcomes. No significant associations were found between baseline BP and the composite outcomes. Using MSMs with time-updated SBP for analysis, a U-shaped association was found. In reference to SBP 110-119 mmHg, hazard ratios (95% confidence intervals) for the SBP categories <110, 120-129, 130-139 and ≥140 mmHg were 1.48 (1.02-2.17), 1.13 (0.80-1.60), 2.21 (1.54-3.16) and 2.91 (1.94-4.35), respectively. The trend was more prominent in patients with proteinuria ≥1 g/day and eGFR ≥60 mL/min/1.73 m2. After analyzing time-updated diastolic BP, no similar trend was observed. CONCLUSIONS: In patients with IgAN, intensive BP control during the treatment period may retard the kidney disease progression, but the potential risk of hypotension still needs to be considered.

Comparison between hydroxychloroquine and systemic corticosteroids in IgA nephropathy: a two-year follow-up study.

BACKGROUND: Hydroxychloroquine (HCQ) is recommended as a treatment for IgA nephropathy (IgAN) to control proteinuria. The long-term effects of HCQ compared to systemic corticosteroid therapy remain unclear. METHODS: We conducted a retrospective case‒control study at Peking University First Hospital. Thirty-nine patients with IgAN who received HCQ for at least 24 months without corticosteroids (CSs) or other immunosuppressive agents were included. Thirty-nine matched patients who received systemic CS therapy were selected using propensity score matching. Clinical data over a 24-month period were compared. RESULTS: In the HCQ group, the level of proteinuria decreased from 1.72 [1.44, 2.35] to 0.97 [0.51, 1.37] g/d (-50.5 [-74.0, -3.4] %, P < 0.001) at 24 months. A significant decline in proteinuria was also found in the CS group, but no significant differences were found between the HCQ group and CS group in the levels of proteinuria (0.97 [0.51, 1.37] vs. 0.53 [0.25, 1.81] g/d, P = 0.707) and change rates (-50.5% [-74.0%, -3.4%] vs. -63.7% [-78.5%, -24.2%], P = 0.385) at 24 months. In addition, the decline rates of eGFR between the HCQ and CS groups were comparable (-7.9% [-16.1%, 5.8%] vs. -6.6% [-14.9%, 5.3%], P = 0.758). More adverse events were observed in the CS group. CONCLUSIONS: Long-term use of HCQ can maintain stable renal function with minimal side effects. In patients who cannot tolerate corticosteroids, HCQ might be an effective and safe supportive therapy for IgAN.

The clinical and pathological characteristics of IgA nephropathy patients in Tibet.

BACKGROUND: There are few studies on immunoglobulin A nephropathy (IgAN) at high altitude. This study aimed to analyze the clinical and pathological characteristics of IgAN between Tibet and Beijing, which provided a basis for improving diagnosis and treatment in Tibet. METHOD: The clinical and pathological data of 80 patients from the People's Hospital of Tibet Autonomous Region (Tibetan group) and 991 patients from Peking University First Hospital (Beijing group) with IgAN proven by renal biopsy were compared retrospectively between January 2016 and July 2020. The kidney biopsy tissue was sent to the Department of Nephrology, Peking University First Hospital for pathological evaluation. RESULTS: The proteinuria (2.9 [2.0, 4.9] vs. 1.1 [0.5, 2.4] g/day, P < 0.001) in the Tibetan group was significantly higher than that in the Beijing group. The serum albumin (30.4 ± 7.7 vs. 38.2 ± 5.5 g/L, P < 0.001) was significantly lower in the Tibetan group. The eGFR (77.7 ± 37.8 vs. 62.1 ± 33.6 ml/min/1.73 m2, P = 0.001) was higher in the Tibetan group. The percentage of patients with nephrotic syndrome in the Tibetan group was significantly higher than that in the Beijing group (33.8% vs. 4.7%, P < 0.001). CONCLUSION: There are differences in the clinical and pathological characteristics of IgAN between plateau and plain regions.

The efficacy and safety of hydroxychloroquine in pregnant patients with IgA nephropathy: A retrospective cohort study.

AIM: Hydroxychloroquine (HCQ) is used to control proteinuria in IgA Nephropathy (IgAN) However, its efficacy and safety in pregnant IgAN patients remains unknown. This study aimed to verify the safety of HCQ in pregnant IgAN patients and compare renal function and pregnancy outcomes with those of patients not treated with HCQ. METHODS: We retrospectively reviewed medical records of all pregnant IgAN patients and singleton gestations at Peking University First Hospital from 2003-2021. Patients who did and did not receive HCQ treatment during pregnancy were compared. RESULTS: We found no significant pre- or post-pregnancy differences in proteinuria or renal function between the two groups. However, the HCQ (+) group had higher proteinuria at the time of kidney biopsy (2.04 [1.26, 2.56] g/d vs. 0.80 [0.44, 1.11] g/d, P < .001); the proteinuria level at HCQ therapy initiation was also higher than that at the beginning of pregnancy (1.87 [1.30, 2.59] g/d vs. 1.08 [0.75, 1.50] g/d, P = .001). Despite no difference in preterm birth, birth weight, preeclampsia or postpartum haemorrhage, the proportion of patients with a previous history of spontaneous abortion was higher in the HCQ (+) group than in the HCQ (-) group (48.0% vs. 20.6%, P = .010). The eGFR (regression coefficient, 0.981; 95%CI 0.964-0.998) was a predictive factor for obstetrical complications. CONCLUSION: HCQ is safe for IgAN treatment during pregnancy with effective reduction of proteinuria. HCQ might also be helpful in patients with a history of spontaneous abortion.