Validation of a hand-held point of care device for lactate in adult and pediatric patients using traditional and locally-smoothed median and maximum absolute difference curves. Clin Chim Acta 2017 May;468:145-149
Date
02/27/2017Pubmed ID
28235428DOI
10.1016/j.cca.2017.02.015Scopus ID
2-s2.0-85014381454 (requires institutional sign-in at Scopus site) 14 CitationsAbstract
BACKGROUND: Lactate is commonly used in septic patients and is a viable biomarker for trauma patients. Its pre-hospital use could assist triaging and managing patients with these conditions.
METHODS: We evaluated the analytical performance of the point-of-care (POC) StatStrip Xpress Lactate Meter (Nova Biomedical) and compared it to the ABL 800 (Radiometer). We measured lactate in 250 adult and 250 pediatric whole blood samples in 2 laboratories. The performance of the POC meter was assessed by traditional linear regression and Bland-Altman plots, and locally-smoothed (LS) median absolute difference and maximum absolute difference (MAD and MaxAD) curves.
RESULTS: The StatStrip was linear with acceptable reproducibility at clinically relevant concentrations. Correlation with the ABL800 showed a negative bias for both populations with slope, bias ±SD (% bias) of 0.78, -0.4±0.7 (-14.5%) in children and 0.80-0.3±0.6 (-13.3%) in adults. The proportional bias appeared more significant at concentrations >4mmol/l (36.0mg/dl). The StatStrip misclassified 7.6 and 8.8% pediatric and adult samples, respectively, to lower risk categories defined using guidelines driven cut-offs. The LS MAD curves identified one breakout, concentration where the LS MAD exceeds the total allowable error limit of 0.3mmol/l (2.7mg/dl), at lactate concentrations of 3.8 and 3.2mmol/l (34.2 and 28.8mg/dl) in the pediatric and adult curves, respectively. Breakthroughs, points at which the LS MaxAD curve exceeds the 95th percentile of MaxADs, occur at concentrations above 7.5mmol/l (67.6mg/dl) for both populations where the performance of the POC meter became erratic. We concluded that if serial lactate measurements are performed, the same method should be used for baseline and follow up measurements. The LS MAD and LS MaxAD curves allowed visual and quantitative mapping of the performance of the lactate POC meter over the range of concentrations measured.
CONCLUSIONS: This approach seems useful for the identification of points at which the performance of a POC meter differs significantly from a comparison method and thresholds of poor analytical performance.
Author List
Colon-Franco JM, Lo SF, Tarima SS, Gourlay D, Drendel AL, Brook Lerner EAuthors
Amy L. Drendel DO Interim Chief, Professor in the Pediatrics department at Medical College of WisconsinDavid M. Gourlay MD Chief, Professor in the Surgery department at Medical College of Wisconsin
Sergey S. Tarima PhD Associate Professor in the Institute for Health and Equity department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AdultBlood Chemical Analysis
Child
Humans
Lactic Acid
Point-of-Care Systems
Statistics as Topic