COST AND HEALTHCARE RESOURCE USE IN PATIENTS WITH IGA NEPHROPATHY: A SYSTEMATIC LITERATURE REVIEW

IgA nephropathy (IgAN) is a rare, progressive kidney disease that can lead to kidney failure (KF). The aim of this systematic review was to assess costs and healthcare resource use (HCRU) associated with IgAN.

A comprehensive literature search was performed in Embase, MEDLINE, PubMed and Cochrane databases from Jan 1st, 2000, to July 8th, 2024. Additionally, key conferences and health technology assessment websites were searched. Studies reporting data on costs and HCRU were included in this review. The quality of the included studies was assessed using the assessment tool developed by the National Institute of Health. All costs were converted to 2024 USD using purchasing power parity and inflation adjustments.

A total of 17 studies were included. Majority of the studies (n=13) were retrospective cohort studies. The mean patient age ranged from 30 to 62 years, and the mean estimated glomerular filtration rate ranged from 9.1 to 58.5 mL/min/1.73m². Fifteen studies reported data on HCRU. Two studies were rated as high quality; the rest were moderate.

In the US, over 70% of IgAN Medicare patients were hospitalized and more than 60% visited the emergency department during a year. The mean annual number of outpatient visits and pharmacy claims increased with chronic kidney disease (CKD) stage (1.7 outpatient visits in stage 2 to 8 visits in stage 5/KF, 2.6 pharmacy claims in stage 3 to 5 claims in stage 5/KF). Another US study reported that patients on systemic glucocorticoids (SGC) had significantly more outpatient visits, inpatient visits, and emergency department admissions compared to the non-SGC group (p<0.0001). Similarly, 8.8% of patients in a Chinese study treated with immunosuppressants were hospitalized for severe infections. The mean annual number of outpatient physician visits ranged from 5.8 (US) to 9.1 (Japan), while annual hospitalization rates varied between 8% (US) and 44% (China). In a study from the UK, higher HCRU was reported in more advanced CKD stages and with higher proteinuria levels. Mean length of hospital stays (LoS) ranged from 10.6 days in China to 26 days in the US. A mean LoS of 11.4 days was reported in Japanese patients who underwent tonsillectomy followed by intravenous methylprednisolone.

Cost data was reported in 13 studies. In the US, the average annual healthcare costs per patient was $34,891.4, mainly from inpatient ($14,548.1) and outpatient ($14,222.5) visits. Another US study showed higher annual costs in patients with proteinuria >=1 g/d ($4,424.3) vs. patients with proteinuria <1g/d ($1,727.3; p=0.01), and costs increased with CKD stages (stage 1: $2,502.6 vs. stage 5/KF: $12,688.3; p<0.001). The productivity loss reported was 31.4%. Similarly, a study from the UK also found higher annual costs in patients with proteinuria >=1 g/day ($22,714.6) vs. patients with proteinuria <1g/d ($5,078.5) and higher costs in CKD stage 5 ($108,442.1) vs. stage 1 (4,695.2). European patients’ overall work productivity loss was 17.7%. A Japanese study reported higher work time missed and work impairment in patients with proteinuria >=1 g/d (19.9% and 37.5%) vs. patients with proteinuria <1 g/day (3.5% and 15.3%). A cost comparison across the US and the UK is provided in table 1, which revealed that emergency and outpatient visit costs were significantly higher in the US compared to the UK.

IgAN significantly increases healthcare costs and resource use, especially with disease progression and higher proteinuria.