CHICAGO — As in outpatients, cystatin C levels appear to offer additional prognostic information in patients admitted with heart failure exacerbations, according to an analysis of 240 consecutive inpatients.
Although there was no significant association between the serum protein levels on admission and the study's primary end point of length of hospitalization, cystatin C was more predictive of all-cause mortality and the combined end point of readmission or death than was creatinine, Dr. Daniel J. Brotman and his colleagues reported in a poster at the annual meeting of the Society of Hospital Medicine.
Patients in the highest quartile of cystatin C (mean 2.44 mg/L) were at significantly increased risk of death (hazard ratio 2.07) and of readmission or death (HR 1.61) during the first year after admission, compared with those in the lower three cystatin C quartiles (mean 0.66-1.43 mg/L).
The association between cystatin C and the risk of readmission or death remained significant on multivariate analysis after adjustment for age, race, gender, and creatinine level (HR 1.65), according to Dr. Brotman, director of the hospitalists program at Johns Hopkins Hospital in Baltimore. The relationship also remained significant when ejection fraction was included in the model.
Cystatin C level has been shown to be a stronger predictor of the risk of death and cardiovascular events in elderly patients, compared with creatinine level (N. Engl. J. Med. 2005;352:2049-60). Accumulating evidence also supports its use as an alternative and more sensitive endogenous marker, compared with serum creatinine, for the estimation of glomerular filtration rate.
In the current analysis, there was a trend toward increased risk of readmission or death (HR 1.44) for patients in the top quartile of creatinine (mean 2.0 mg/dL), compared with those in the lower three creatinine quartiles (1.0-1.3 mg/dL), but this difference did not reach statistical significance.
The combination of cystatin C and creatinine, however, was significantly more predictive of the combined end point of readmission or death than was either variable alone (HR 1.81).
“We are looking into whether serial changes in this biomarker during the course of hospitalization will have any potential clinical utility,” Dr. Brotman said in an interview. Clinical application is currently limited, as most labs do not routinely test for cystatin C.
Dr. Brotman disclosed receiving research funding from Siemens Healthcare Diagnostics Inc., serving on the hospitalist leadership panel for Quantia Communications LLC, and being on the advisory boards of several pharmaceutical companies.
The combination of cystatin C and creatinine was more predictive of readmission or death than was either one alone.
Source DR. BROTMAN