Abstract
Background and Aims
Immunoglobulin A nephropathy (IgAN) is a chronic glomerular disease that affects approximately 100,000-200,000 people in the US. Approximately 15-40% of IgAN patients will eventually progress to end stage kidney disease (ESKD) within 10-20 years of diagnosis, and there is currently no targeted therapy for this disease. Decreased kidney function, persistent proteinuria and hypertension are some of the clinical manifestations of IgAN, and with demographic aspects (e.g. ethnicity) are considered as predictors of disease progression. The aim of this study is to better understand the demographic and clinical characteristics of IgAN patients in the US identified via physician notes.
Method
This is a descriptive, retrospective study of adult (≥ 18 years) IgAN patients in Optum® Electronic Health Records (EHRs), between January 2007 and December 2019. Optum® EHRs contain de-identified clinical and medical administrative data from 96 million people in 50 states that come from more than 140,000 providers at 740 hospitals and over 7,000 clinics. Identification of IgAN patients is challenging because there are no specific ICD codes for this disease so we used natural language processing of physician notes and chose patients with at least two IgAN records with the first one considered to be the index date, and no negative mention, as well as a biopsy procedure. Here, we present the baseline demographic and clinical characteristics of the identified patients up to 12 months before and at the index date.
Results
A total of 1803 patients with a biopsy record (22% of all patients with at least two IgAN records in their EHRs in our study) were included in this analysis; results are presented in Table 1. The mean age was 48 years, and the majority of patients were male (60.9%) and white (75.7%). Proteinuria levels of ≥1 g/day were found in 34% of patients. The mean eGFR was 45 ml/min/1.73m2 and 21.6% of patients had severe deterioration of kidney function (eGFR <15). The mean creatinine level was 3 mg/dL. Pain, edema and fatigue/tiredness were reported in 39.6%, 18.1% and 13.4% of patients, respectively. Hypertension was reported in 73% of patients. Based on the ICD 9 (585.6) and ICD-10 (N18.6) codes for diagnosis, 17.5% of patients had ESKD in our study.
Conclusion
In our cohort, a significant proportion of patients were found to have high proteinuria levels and severe deterioration of kidney function or ESKD. Moreover, edema and fatigue were recorded for a noticeable proportion of patients. In addition to the commonly reported symptoms, our study also found that pain was reported in a high proportion of patients. These findings highlight the clinical and symptom burden to patients with IgAN, suggesting that future targeted interventions are needed to reduce the burden and delay the progression of this disease.
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