373. Evaluation of the StatSensor Xpress for the point of care determination of capillary creatinine concentration in a pregnant population

Introduction Early identification of Acute Kidney Injury during pregnancy (P-AKI) is critical to reduce adverse maternal and fetal outcomes. The StatSensor Xpress (Nova Biomedical) is a handheld device that may improve feasibility of rapid, serial creatinine concentration measurement, especially in low resource settings with a high incidence of P-AKI. Prior to implementation the device requires validation in a pregnant population. Objective To evaluate the performance of the StatSensor Xpress creatinine analyser in capillary blood compared to an enzymatic serum assay, in a pregnant population. Methods Serum and capillary blood samples were obtained prospectively from pregnant participants at antenatal obstetric clinics, and non-pregnant controls. Repeatability was assessed in quality control lots and venous blood from three participants at low (50 μmol/L), mid (90 μmol/L) and high (200 μmol/L) concentrations. Creatinine concentration was determined using an enzymatic reference method in serum samples and StatSensor in capillary blood, as per manufacturer’s specifications. Agreement was assessed by concordance and construction of Bland–Altman plots. A retrospective adjustment factor was separately applied to evaluate the inbuilt offset function. Results Coefficients of variation (CV) from repeatability analysis, ranged from 2.1 to 3.0%CV in aqueous solution and 4.0%CV, 3.0%CV and 4.1%CV in whole blood samples of low, mid and high creatinine concentrations respectively. Lin’s concordance correlation coefficients between the methods were 0.95 (n = 15), and 0.96 (n = 11) when non-pregnant participants were excluded. The median difference between methods was +12 μmol/L. Discussion The StatSensor met desirable criteria for precision and accuracy. 95% limits of agreement were adequate once systematic bias was corrected for by retrospective application of an adjustment factor, which can be used for future analysis. Device performance may be superior in pregnancy due to the lower serum creatinine concentration observed secondary to glomerular hyperfiltration. Findings require replication in a larger population with prospective evaluation of the offset function.