A high-risk profile from the urinary biomarker CKD273 was significantly associated with an increased risk of microalbuminuria in patients with diabetes, according to findings from a multicenter European trial.
“Although microalbuminuria is the earliest clinical index of renal damage, histological changes might already be advanced by the time it is detectable. Thus, earlier identification of at-risk individuals is essential to guide targeted preventive therapy,” wrote Nete Tofte, MD, of the Steno Diabetes Center in Copenhagen, and colleagues.
“Increases in urinary albumin to microalbuminuria levels, or higher, are not only strongly associated with progression to more serious clinical endpoints, such as clinically significant loss of renal function and eventually, end-stage kidney disease, but also with an increased risk of cardiovascular complications,” the researchers noted in the Lancet Diabetes & Endocrinology.
They identified 1,775 adults with type 2 diabetes who had normal albumin levels and preserved renal function at baseline. The average age of the patients was 62 years, and 62% were men. The participants underwent urine proteomics testing via capillary electrophoresis–mass spectrometry analysis to generate a renal risk profile based on 273 peptides (CKD273). On the basis of their CKD273 scores, 216 patients (12%) were designated to the high-risk group, and 1,556 (88%) to the low-risk group.
Over a median follow-up of 2.5 years, 61 patients (28%) in the high-risk group progressed to microalbuminuria (the primary endpoint), compared with 139 patients (9%) in the low-risk group.
Of the original 216 high-risk patients, 209 were randomized to treatment with 25 mg of the mineralocorticoid receptor antagonist spironolactone (102 patients) or placebo (107) to examine whether spironolactone would stall progression to microalbuminuria.
The researchers found, however, that spironolactone did not prevent progression to microalbuminuria. In all, 26 of the 102 patients (25%) patients in the spironolactone group developed microalbuminuria, and 35 of the 107 patients (33%) in the placebo group developed it (hazard ratio, 0.81; 95% confidence interval, 0.49-1.34; P = .41).
The total number of adverse events was not significantly different between the spironolactone and placebo groups (312 vs. 321, respectively), although more patients in the spironolactone group experienced adverse events that led to drug discontinuation (25 vs. 9, respectively).
The study findings were limited by several factors, including the use of a single urine sample for risk stratification; the lower-than-expected number of high-risk patients; not testing spironolactone in the low-risk group; and the fact that microalbuminuria, although an accepted surrogate for diabetic kidney disease, is not approved as such by regulatory agencies, the researchers noted. However, the results were strengthened by the large study population and prospective design, as well as the additional register-based follow-up that is planned when possible.
In an accompanying editorial, Susanne B. Nicholas, MD, of the University of California, Los Angeles, reiterated that microalbuminuria cannot be used to track responses to therapy even if it is an acceptable indicator of potential renal damage.
“In fact, regression from microalbuminuria to normoalbuminuria is more likely than progression toward overt proteinuria, [which exposes] a need for a more dependable biomarker for diabetic kidney disease,” she wrote.
However, Dr. Nicholas supported the potential of proteomics as a tool “that could bridge the gap between discovery of diabetic kidney disease – possibly providing a panel, rather than a single or few urinary indicators of structural changes that predate microalbuminuria – and response to therapy, given the promise of targeted therapies for this complex disease.” Additional research into patient selection, comparators to verify findings, and cost containment is needed before proteomics can become part of routine care, she added.
The study was supported by the European Union Seventh Framework Programme. Dr. Tofte had no financial conflicts to disclose. Several other authors disclosed relationships with multiple companies, including Amgen, AstraZeneca, Boehringer Ingelheim, Novo Nordisk, and Sanofi. Dr. Nicholas had no financial conflicts to disclose.
SOURCES: Tofte N et al. Lancet Diabetes Endocrinol. 2020 Mar 2. doi: 10.1016/S2213-8587(20)30026-7; Nicholas SB. Lancet Diabetes Endocrinol. 2020 Mar 2. doi: 10.1016/S2213-8587(20)30067-X.