Steady prevalence masks changes in diabetic kidney disease
medwireNews: Patients with diabetic kidney disease have become less likely to have albuminuria but more likely to have a reduced estimated glomerular filtration rate (eGFR) over recent years, shows an analysis of NHANES data.
As reported in JAMA, the overall prevalence of diabetes increased between the 1988–1994 and 2009–2014 phases of the US national survey, from 6.0% to 9.8%. But the prevalence of kidney disease among these 6251 adults did not, at corresponding rates of 28.4% and 26.2%.
However, the prevalence of albuminuria fell significantly from 20.8% to 15.9% over this period, although this was driven by reductions among patients younger than 65 years.
Ian de Boer (University of Washington, Seattle, USA) and study co-authors suggest this decline could be caused by better diabetes management. Use of antidiabetic agents increased over the course of the study, they note, reflected in improved glycaemic control, which has been associated with a reduced albuminuria risk in clinical trials.
And supporting this further was the lack of a significant decline in albuminuria among Black and Hispanic patients, consistent with findings that these groups are less likely than White patients to receive evidence-based diabetes medications.
In contrast with the trend for albuminuria, the prevalence of reduced eGFR increased over the study period, from 9.2% to 14.1%, while that of severely reduced eGFR (30 mL/min per 1.73 m2) rose from 1.0% to 2.7%. This trend was consistent regardless of age or ethnicity.
The researchers note that the age distribution of the patients did not change over time, making increasing age an unlikely explanation for the declining kidney function.
“It is possible that hemodynamic effects of [renin-angiotensin-aldosterone system] inhibitors and improved blood pressure control could contribute to lower eGFR”, they speculate. “Alternatively, an increasing duration of diabetes may be contributing to kidney damage.”
Diabetes duration did indeed increase over time, with the proportion who had lived with it for at least 20 years increasing from 8.9% to 14.9%. But as the patients were on average no older, the team concludes that the average age at diabetes onset has fallen.
“[R]educed eGFR was associated with retinopathy and macrovascular disease, regardless of whether albuminuria was present, suggesting that reduced eGFR is occurring in the setting of other long-term diabetes complications”, say de Boer et al.
They suggest that new therapies may be needed to combat the increasing prevalence of reduced eGFR.
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