Cardiac biomarker may also be predictive in CKD
Tuesday, 19 June 2012- NT-proBNP, a biomarker predictive of adverse cardiac events, may also be predictive of unfavorable chronic kidney disease outcomes in those with type 2 diabetes, Japanese researchers found.
Of the 109 diabetes patients in the study, the 14 patients who experienced new cardiovascular events or death were more likely to to have NT-proBNP levels above 153 pg/mL, according to Dr. Kumiko Hamano, from Kanto Rosai Hospital in Kawasaki, Japan, and colleagues.
Another 14 patients who reached the renal endpoint of a 30% or more decrease in estimated glomerular filtration rate (eGFR) were significantly more likely to have NT-proBNP levels above 120 pg/mL, Hamano and colleagues reported here at the annual meeting of the American Diabetes Association.
The odds ratio that an NT-proBNP level at or above 120 pg/mL (the optimal renal threshold) would predict both renal and cardiovascular outcomes at 5 years was 5.4. For levels at or above 153 pg/mL (the optimal cardiovascular threshold), the odds ratio for predicting both renal and cardiovascular outcomes was 9.8.
"It is possible to stratify diabetic patients by simple measurement of NT-proBNP, which is reproducible and inexpensive and enables cardiovascular disease prevention and chronic kidney disease prevention as well," Hamano and colleagues concluded.
They said more studies should be conducted to confirm the cutoff values.
Hamano's team had previously validated NT-proBNP as a marker for silent myocardial ischemia (Diabetes Metab Res Rev 2010;26: 534–539). They concluded at the time that the "outstandingly high negative predictive value of NT-proBNP enables us to focus on diabetic patients with occult coronary disease, independently of microalbuminuria."
Because of the "cardiorenal syndrome" that suggests cardiovascular disease accelerates chronic kidney disease progression, while chronic kidney disease itself amplifies cardiovascular disease, Hamano and colleagues sought to determine whether NT-proBNP could be a marker for both cardiac and kidney disease progression.
For the current study, they recruited 109 consecutive patients at one center with type 2 diabetes and stage 1 or 2 chronic kidney disease. Patients had a mean age of 62, a mean duration of diabetes of 10 years, a mean hemoglobin A1c (HbA1c) of 9.1%, and a mean serum creatinine of 0.76 mg/dL.
The median baseline NT-proBNP level for those whose renal function declined during the 5 years of follow-up was 169 pg/mL compared with 52 pg/mL for those who remained stable.
Several significant characteristics separated patients whose biomarker levels were above or below the optimal cutoff of 120 pg/mL:
• Age -- median 74 versus 66
• eGFR -- 68.8 min/mL versus 74 min/mL
• Creatinine -- 0.86 mg/dL versus 0.75 mg/dL
Gender made no difference, nor did baseline HbA1c levels (7.8 versus 7.7%), Hamano reported.
Patients who experienced a new cardiovascular event had mean baseline levels of NT-proBNP of 142 pg/mL compared with 44 pg/mL for those without new events and 128 pg/mL for those with past cardiovascular events. There were no statistically significant patient characteristics that differed between those above or below the cutoff threshold.
Hamano and colleagues noted that the NT-proBNP as a marker for kidney disease would be easily applicable because it is already an established cardiac screening tool with good sample stability.
Source: R. Komi, et al., "NT-proBNP: A potential bardiorenal biomarker in the management of diabetes," American Diabetes Association 2012; abstract 447-P.