Albuminuria change is a strong cardiovascular risk indicator in diabetes

By Eleanor McDermid, Senior medwireNews Reporter

Changes in albuminuria predict cardiovascular mortality and morbidity over and above glucose levels and blood pressure, say researchers.

The team analysed data from two randomised trials of antihypertensive agents (ONTARGET and TRANSCEND), which included 22,984 patients, of whom 36.8% had high-risk diabetes (diabetes plus end-organ damage).

Roland Schmieder (University Hospital of the University Erlangen-Nuremberg, Germany) and co-workers found that the additive effects of diabetes and hypertension (based on systolic blood pressure) on outcomes were weaker than the effect of worsening or persistent albuminuria alone.

“[T]he implications of our findings are that evaluating changes in albuminuria over time may be a valuable monitoring tool to assist clinicians in following patients with diabetes at increased cardiovascular risk”, they write in Diabetologia.

However, they note that overall risk was highest in patients with all three factors, who had about a fivefold increased risk of cardiovascular events and nearly a 10-fold increased risk of renal events, after accounting for confounders, compared with patients who had none of the risk factors.

For example, the average combined annual cardiovascular morbidity and mortality rate was 2.54 in patients with none of the three risk factors whose fasting blood glucose was lower than 5.6 mmol/L, and 4.35 in those with diabetes and hypertension but normoalbuminuria. It was slightly higher, at 4.88, in those who did not have diabetes or hypertension but who developed microalbuminuria during follow-up, and was markedly higher again in those with persistent microalbuminuria, at 8.38.

Glucose levels were associated with mortality and cardiovascular and renal outcomes after accounting for confounders. However, patients who improved from having microalbuminuria to normoalbuminuria were 35% and 32% less likely to die of any or cardiovascular causes, respectively, compared with patients who developed new microalbuminuria, after accounting for confounders including diabetes.

Likewise, improving albuminuria was independently associated with a 28% and 36% reduction in risk for cardiovascular and renal outcomes, respectively, relative to deteriorating albuminuria.

“This result indicates the effectiveness of albuminuria reduction in attenuating risk across a wide range of glucose levels”, say the researchers.

Schmieder and team also highlight that the predictive ability of albuminuria in patients with diabetes and hypertension was independent of diastolic blood pressure. They say this “suggests that reducing urinary albumin excretion may be a valid therapeutic target, in addition to [blood pressure] control.”

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