medwireNews: People with type 2 diabetes and reduced kidney function in the absence of albuminuria have an increased risk for mortality and major adverse cardiovascular events (MACE), despite a low risk for end-stage renal disease (ESRD), research shows.
The analysis found that the 432 ACCORD trial participants who had an estimated glomerular filtration rate (eGFR) below 60 mL/min per 1.73 m2 but a urine albumin-to-creatinine ratio (UACR) below 3.4 mg/mmol (30 mg/g) had a slower rate of kidney function decline than the 2724 people who had normal baseline eGFR.
During follow-up lasting an average of 8.8 years, eGFR declined by an annual average of 0.60 versus 1.31 mL/min per 1.73 m2 in the subgroups with nonalbuminuric chronic kidney disease (CKD) and with normal kidney function, respectively.
Thus, people with nonalbuminuric CKD had a lower crude rate of ESRD than people with normal kidney function, at 1.81 versus 2.60 per 1000 person–years, although the adjusted hazard ratio of 0.76 was not statistically significant.
“There is no easy explanation for this observation other than the relatively higher proportion of RAAS [renin-angiotensin-aldosterone system] blockade usage, lower prevalence of smoking, and [cardiovascular disease] history in nonalbuminuric CKD compared with the albuminuric CKD,” say Oyunchimeg Buyadaa (Baker Heart & Diabetes Institute, Melbourne, Victoria, Australia) and co-researchers.
They suggest that the renal decline with people without albuminuria might be related to age more than progressing disease, or that these people may have “as-yet-unidentified renoprotective features, the elucidation of which might further our understanding of the progression of kidney disease in diabetes.”
By contrast, the 2867 people with albuminuria alone had a significant 1.72-fold increased risk for ESRD and the 345 with albuminuria plus reduced eGFR had a 4.52-fold increased risk.
But the slow eGFR decline for people with nonalbuminuric CKD did not protect them from other adverse outcomes. They had a 1.42-fold increased risk for mortality and a 1.44-fold increased risk for MACE compared with people with normal renal function, which were both statistically significant, albeit smaller increases than those seen with albuminuria alone and with reduced eGFR. These two subgroups had respective risk increases of 1.82- and 2.38-fold for mortality and 1.88- and 2.37-fold for MACE.
“Our study demonstrated that those with nonalbuminuric CKD have a slower rate of decline in eGFR than did any other group, including those with normal renal function, suggesting the presence of renoprotective factors,” write the researchers in Diabetes Care.
“However, these individuals still carry a greater risk for all-cause mortality and MACE than do those with normal renal function. With increasingly prevalent nonalbuminuric CKD in diabetes, more studies are warranted to clarify its underlying mechanisms or pathogenesis.”
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