Evaluation of i-STAT Creatinine Assay

Abstract

Background: We evaluated a new, 2-min blood creatinine method using the hand-held i-STAT analyzer. Good results have already been reported using this analyzer for 10 methods including electrolytes, TCO₂, pH, PCO₂, bicarbonate, glucose, hemoglobin and urea for uremic blood, hemodialysate and peritoneal effluent. Methods: Evaluation included study of imprecision and accuracy. Results: Imprecision studies gave excellent results, including those for reproducibility of 6 solutions with a mean of 10 repeats and coefficients of variation (CVs) of 0.4–3.4%, and also the mean of the differences between 33 duplicate blood specimens which was 2.2% of the specimen mean. To assess accuracy, we compared results of 149 tests by i-STAT and Beckman Synchron CX7 methods. The difference between the two means was 2.6% and the mean of all differences was 10.9% with i-STAT results higher, especially when blood creatinine values were <100 µmol/l (1.1 mg/dl) indicating the need for a slightly higher upper limit of the normal range. The correlation coefficient between the two methods was 0.99, the slope 1.0 and the intercept –5.0 µmol/l (–0.06 mg/dl). We assessed the recommended creatinine correction for variation in PCO₂above and below 40 mm Hg, but our results did not suggest the need for such a correction in our range of 27–64 mm Hg; omission would remove a major method disadvantage. Assays of hemodialysate and peritoneal effluent were also satisfactory. Conclusions: The i-STAT creatinine method is simple and rapid and our evaluation showed satisfactory accuracy and precision. However, results were on average slightly higher than for the Beckman Synchron CX7 method.

Comparison of Three Whole Blood Creatinine Methods for Estimation of Glomerular Filtration Rate Before Radiographic Contrast Administration

“…6,7 One of those studies compared concordance of i-STAT whole blood eGFR with plasma eGFR calculated from a Roche IDMS-calibrated creatinine method on a small group of patients (n = 50). This study found that sensitivity for detecting plasma eGFR less than 60 mL/min/1.73 m 2 was 100%, whereas specificity was only 85%.…”

Comparison ofpH, Lactate, and Glucose Analysis of Equine Synovial Fluid using a Portable Clinical Analyzer with a Bench‐Top Blood Gas Analyzer

“…Numerous portable clinical analyzers have been validated for blood gas analysis in horses using whole blood . At least 2 portable clinical analyzers have also been evaluated using peritoneal fluid in horses and people . Validation of a portable clinical analyzer using synovial fluid may be helpful to equine practitioners evaluating synovial infections in the field, because the results of these patient‐side biochemical analytes would help reinforce the clinical suspicion of synovial infection in situations where clinical laboratory support is unavailable.…”

Performance evaluation of all analytes on the epoc® Blood Analysis System for use in hospital surgical and intensive care units

“…A recent review of different POCT instruments that measured creatinine also showed a wide range of biases between handheld and blood gas POCT analyzers and routine laboratory analyzers [ 12 ]. Significant proportional and absolute bias have been reported between the i-STAT hand-held analyzer and the Vitros 750 [ 13 ], Roche Cobas c702 enzymatic method [ [14] , [15] , [16] ], Beckman Synchron CX7 Jaffe method [ 17 ] and the Beckman DxC800 Jaffe assay [ 18 ]. Moreover, significant bias has been reported between the creatinine measured on Nova StatSensor and routine laboratory enzymatic methods [ 16 , [19] , [20] , [21] , [22] , [23] ].…”