StatSensor-i point-of-care creatinine analyzer may identify patients at high-risk of contrast-induced nephropathy

The current study assessed the accuracy of the StatSensor-i (STA) point-of-care creatinine analyzer prior to and following adjustment (offset correction) by linear regression scatter plots produced by the reference samples from patients and volunteers for detecting high risk of contrast-induced nephropathy in patients with an estimated glomerular filtration rate <45 ml/min/1.73 m². Blood samples were obtained from 233 consecutive outpatients scheduled for contrast-enhanced CT studies. Of the 233 patients, 123 patient samples were evaluated prior to adjustment and the other 110 following adjustment. Serum creatinine levels and estimated glomerular filtration rate were measured using the analyzer and compared with the values returned by laboratory tests. Analysis was with the paired t-test, the Pearson correlation coefficient and Bland-Altman plotting. The sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy for detecting patients with an estimated glomerular filtration rate <45 ml/min/1.73 m² were subsequently calculated. Mean serum creatinine levels measured with the analyzer were significantly higher than those returned by laboratory tests before (P<0.0001) and after adjustment (P<0.01). Following adjustment, the difference in serum creatinine values obtained with the STA analyzer and by laboratory methods did not exceed 0.3 mg/dl. Prior to adjustment, 9.7% of the samples were overdiagnosed as having an estimated glomerular filtration rate of <45 ml/min/1.73 m²; following adjustment, the overdiagnosis rate was 2.7%. The sensitivity, specificity, PPV, NPV and accuracy were 100, 89, 50, 100 and 90.2% before and 100, 96.3, 33.3, 100 and 96.4% after adjustment, respectively. With the adjusted point-of-care creatinine analyzer, estimated glomerular filtration rate may be reliably evaluated in the radiology suite.