Prognostic value of UACR depends on availability of cardiac biomarkers
medwireNews: An increased urinary albumin to creatinine ratio (UACR) is significantly and independently associated with an increased risk for cardiovascular outcomes in patients with type 2 diabetes, an analysis of SAVOR-TIMI 53 data shows.
However, when contemporary cardiac biomarkers were taken into account, the additional prognostic value was minimal.
Therefore “the utility of using UACR as a tool for cardiovascular risk assessment in patients with [type 2 diabetes] is dependent on whether established cardiac biomarkers are also being assessed simultaneously,” Benjamin Scirica (Harvard Medical School, Boston, Massachusetts, USA) and co-investigators remark.
Scirica and team analyzed baseline UACR values for 15,760 participants (33% women) of the SAVOR-TIMI 53 trial who were randomly assigned to receive saxagliptin or placebo and followed up for a median 2.1 years.
Around a third (36.8%) of patients had a UACR below 10 mg/g, 24.7% had a level of 10–30 mg/g, 28.1% had a level of 30–300 mg/g, and 10.4% had a level above 300 mg/g.
When evaluated without cardiac biomarkers, the primary composite endpoint of cardiovascular death, myocardial infarction, or ischemic stroke increased significantly with increasing UACR category from 3.9% to 6.9%, 9.2%, and 14.3%, respectively.
With the exception of hospitalization for coronary revascularization, the incidence of all secondary cardiovascular events also increased with increasing UACR category. For example, rates of cardiovascular death increased from 1.4% to 2.6%, 4.1%, and 6.9%, respectively, while rates of hospitalization for heart failure increased from 1.5% to 2.5%, 4.0%, and 8.3%, respectively.
Furthermore, the addition of UACR to a standard clinical model that included estimated glomerular filtration rate but not cardiac biomarkers significantly improved discrimination and reclassification of risk for all endpoints.
When the researchers included baseline levels of N-terminal pro B-type natriuretic peptide (NT-proBNP), high-sensitivity troponin T (hsTnT), and high-sensitivity C-reactive protein (hsCRP), UACR remained significantly associated with cardiovascular outcomes but the relationship was attenuated and the improvements in discrimination and reclassification of risk were minimal.
Writing in JAMA Cardiology, Scirica et al say that this finding “is not unexpected given the strong association between cardiac biomarkers and cardiovascular outcomes in patients with [type 2 diabetes].”
But they point out that cardiac biomarkers are rarely measured in stable patients with diabetes, so UACR could “still offer additional incremental prognostic information.”
They conclude: “Our data indicate that from a prognostic stand point, even low-level elevations in UACR (10-30 mg/L), which would not be classified by contemporary clinical standards as elevated levels of albuminuria, are associated with increased all-cause mortality as well as cardiovascular risk when compared with patients with UACR of less than 10 mg/g and are therefore clinically relevant and successfully identify high-risk patients.”
By Laura Cowen
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