Senior manager Alexion, AstraZeneca Rare Disease Boston, United States
Background: IgA nephropathy (IgAN) is a chronic disease characterized by immune complex deposition resulting in activation of the complement system, triggering inflammation and causing kidney damage. There are no recent studies of IgAN long-term follow-up based upon US real-world data.
Objectives: To characterize major clinical outcomes of newly diagnosed patients with IgAN based upon a large electronic medical database.
Methods: A US cohort of patients with IgAN from TriNetX database included men and women ages 18 to 75 years with ICD-10 diagnosis codes N02.1, N02.2, N02.3, N02.5, N02.8, N02.9 and renal biopsy performed anytime during the study period October 1, 2015 to Nov 15, 2021. Continuous observation in the database ≥26 months prior to the first diagnosis date and 3 months after the first diagnosis date were required. Patients with a history of estimated glomerular filtration rate (eGFR) < 15 mL/min/1.73m2, dialysis, or kidney transplant and glomerular disease other than IgAN were excluded. Baseline was defined as 1 year prior to the initial IgAN diagnosis. Follow-up starts at the date of the first diagnosis. Clinical outcomes including proteinuria, eGFR, dialysis, kidney transplant and in-hospital death were extracted during the follow-up.
Results: 252 IgAN patients were identified, mean diagnosis age was 46 years, 56% male, 77 % Caucasian, 10% Hispanic, average follow-up was 4.6 years, 222 patients had at least 3 years of follow-up. At diagnosis, 37% had hypertension, 11% had diabetes, mean eGFR was 58 mL/min/1.73m2, mean proteinuria was 3.0 g/day. Within 6 months of diagnosis, 44% of patients were prescribed corticosteroids, 52% of patients were prescribed angiotensin II receptor blockers, and 5% of patients were prescribed ACE inhibitors. Percentage of patients with proteinuria ≥ 1g/day decreased from 64% to 50% within three years. eGFR decreased to < 15 mL/min/1.73m2 in 35% of patients, mean time to this decrease being 1.3 years after initial diagnosis. The fastest decline of eGFR was observed during the first year of follow-up. The eGFR declined 9% (58 to 53 mL/min/1.73m2) during the first year then stayed relatively stable up to 3 years. After initial diagnosis, 15% of patients required dialysis, mean time to initiation of dialysis was 2.2 years, 10% of patients required kidney transplant, mean time to kidney transplant was 1.9 years, mean time to death (in-hospital, 8% of the patients) was 3.6 years following initial diagnosis.
Conclusions: In newly diagnosed patients with IgAN in the US, almost half received corticosteroids and one-third of patients experienced worsening disease including markedly decreased eGFR, dialysis, kidney transplant, or death over the course of 4.6 years of follow up.
