Proteinuria Trajectory Predicts Progression of IgA Nephropathy

Proteinuria trajectory is a major predictor of disease progression in children and adults with IgA nephropathy (IgAN), according to study findings published in the Clinical Journal of the American Society of Nephrology.

The researchers used data from patients enrolled in CureGN, a multicenter, observational cohort study, to evaluate the relationship between proteinuria patterns and disease progression in participants with IgAN and IgA vasculitis with nephritis (IgAVN).

“Identifying patients with IgA nephropathy at risk for disease progression is critical for clinical decision making, risk-based patient counseling, and optimal enrollment of clinical trials,” Dorey A. Glenn, MD, MPH, and co-authors said.

Dr. Glenn, an assistant professor of medicine at the University of North Carolina at Chapel Hill, and their colleagues from across the United States, Canada, Italy, and Poland, categorized patients into trajectory groups based on proteinuria measurements over 2 years using latent class trajectory modeling.

Children (n=234) and adults (n=368) with IgAN and IgAVN were analyzed separately across four cohorts: full, incident, prevalent, and histology.

In addition, they measured the predicted estimated glomerular filtration rate (eGFR) slope. Cox proportional hazard models were used to model time to kidney failure or 40% eGFR decline in adults.

The researchers identified three proteinuria trajectory groups among adults. Group 1 had the lowest proteinuria levels (interquartile range [IQR], 0.1–0.4 g/g), while Group 2 had intermediate levels (IQR, 0.5–1.5 g/g) and Group 3 had the highest levels (IQR, 1.8–4.1 g/g).

Furthermore, the average predicted time to eGFR less than 15 mL/min/1.73 m² was greater than 90 years, 16 years, and 8 years for adult trajectory Groups 1, 2, and 3, respectively. In children, the predicted time to eGFR was greater than 90 years (Group 1), 67 years (Group 2), and 11 years (Group 3).

After adjusting for age, baseline eGFR, immunosuppression exposure, and hypertension in adults, the researchers observed that patients in Group 3 had a significantly higher hazard of progressing to kidney failure or a 40% decline in eGFR compared with Group 2 in the full, prevalent, and histology cohorts. However, there was no association with progression in the incident cohort.

Source: Dorey GA, et al. Clin J Am Soc Nephrol. doi:10.2215/CJN.0000000707