Even albuminuria within normal limits associated with risk for CKD progression, study finds

Patients with chronic kidney disease (CKD) and albuminuria of 15 to 30 mg/g had more than double the risk of CKD progression over 10 years compared with those with a urine albumin-creatinine ratio of 0 to less than 5 mg/g.

Even with albuminuria less than 30 mg/g, patients with chronic kidney disease (CKD) had excess risk for progression, which increased in a linear fashion with higher levels of albuminuria, a study found.

The prospective cohort study was conducted at seven U.S. clinical centers among 1,629 patients with CKD (estimated glomerular filtration rate [eGFR], 20 to 70 mL/min/1.73 m2) and urine albumin-creatinine ratio (UACR) less than 30 mg/g. (Researchers used baseline spot urine albumin divided by spot urine creatinine to calculate UACR.)

Normoalbuminuria was defined as less than 30 mg/g, moderate albuminuria was defined as 30 to 300 mg/g, and severe albuminuria was defined as greater than 300 mg/g. CKD progression was defined as a composite of 50% eGFR decline or kidney failure (dialysis or kidney transplantation). Results were published April 2 by Annals of Internal Medicine.

Over a median follow-up of 9.8 years, 182 of 1,629 participants experienced CKD progression. The 10-year adjusted cumulative incidence of CKD progression was 8.7% (95% CI, 5.9% to 11.6%) for UACR levels of 0 to less than 5 mg/g, compared to 11.5% (95% CI, 8.8% to 14.3%) for 5 to less than 15 mg/g and 19.5% (95% CI, 15.4% to 23.5%) for 15 mg/g or more. Patients with a UACR of 15 mg/g or more had 7.9% (95% CI, 3.0% to 12.7%) absolute higher risk of progression than those with UACR of 5 mg/g to less than 15 mg/g, and 10.7% (95% CI, 5.8% to 15.6%) higher risk than those with UACR of 0 to less than 5 mg/g. Risk of progression increased linearly with baseline UACR levels.

Researchers noted that the study included a diverse cohort of patients with common forms of CKD, had a long follow-up, and benefited from low rates of missing outcome data. However, a limitation was that UACR was measured only once at baseline, and because most of the cohort was already receiving a blood pressure medication, baseline UACR reflected residual albuminuria on treatment and would likely have been higher had participants been untreated.

"These findings underscore the need for future studies to determine the optimal threshold for initiating treatment with antiproteinuric agents and whether the further reduction in albuminuria may improve adverse clinical outcomes in persons with CKD who have normoalbuminuria," the study authors said.