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IgAN is the most common primary glomerulonephritis worldwide with up to 40% of IgAN patients progressing to kidney failure within 20 years following diagnosis. Almost all patients with IgAN are expected to progress to kidney failure during their lifetime, regardless of age or estimated glomerular filtration rate (eGFR) at diagnosis. IgAN is characterized by race/ethnic predilection, heterogeneity in disease progression, and potential race/ethnic variations in treatment response. Previous studies have assessed disease progression in Asian and non-Hispanic white patients; however, there remains a lack of understanding of IgAN disease progression in Hispanic/Latino patients.
In a longitudinal cohort study (1/1/2000-12/31/2021) performed within Kaiser Permanente Southern California members (age≥18 years), a subset of Hispanic/Latino patients with biopsy-proven primary IgAN were identified. Secondary IgAN was excluded. The outcome of interest was the annualized eGFR change with aggressive decline defined as eGFR decline >5 mL/min/1.73 m2/year. The annualized rate of change of eGFR was calculated using an ordinary least squares (OLS) regression method fitted to all eGFR readings for each patient. The slope of the regression line describes the rate of change in kidney function (eGFR) over time. Only outpatient eGFR values starting at baseline were evaluated. A composite kidney outcome was evaluated as 1) ESKD (defined as treatment with dialysis or kidney transplant) or 2) ≥50% decline in eGFR (defined as an eGFR decline ≥50% with a confirmation using a second eGFR decline ≥ 50% at 30 days or more from that initial 50% decline).
A total of 276 adult Hispanic/Latino patients were identified to have biopsy-proven primary IgAN with mean (SD) age 44.9 (14.1) yrs, 50.4% males. The mean (SD) eGFR was 60 (33) mL/min/1.73 m2 and the mean (SD) protein creatine ratio (uPCR) was 2.7 g/g (2.9) with 71.7% having a uPCR ≥1 g/g. Among 247 patients with temporal eGFR data, 34.4% patients had eGFR decline of >5mL/min/1.73 m2/year. The median eGFR change among Hispanic/Latino patients was -3.1 (-6.8,-0.6) mL/min/1.73m2/year. The composite kidney outcome occurred at a rate (95%CI) of 80.8 per 1000 persons-years (65.6, 99.5) with a median (IQR) time to composite outcome event of 2.5 years (0.6,4.8). The median time to ESKD for Hispanic/Latino patients was 3.1 years (0.7,5.5). Median age at ESKD was 46 yrs. This was similar to Asian/Pacific Islanders 3.0 years (.8,6.5) with median age at ESKD 47.1 yrs.
Our findings within a real-world setting, demonstrate that Hispanic/Latino patients with IgAN have a high rate of CKD progression and ESKD. This suggests that disease progression and severity among Hispanic/Latino patients is higher than expected. Although Asian/Pacific Islanders have been reported to have one of the fastest disease progression and burden, our study suggests that more research is needed to understand the unmet needs of Hispanic/Latino patients. This can also elucidate an understanding of whether Hispanic/Latino ethnicity is a risk factor for disease severity, ESKD and CKD progression.