Creatinine standardization: a key consideration in evaluating whole blood creatinine monitoring systems for CKD screening.

Early detection of CKD using point of care creatinine and eGFR testing improves patient management outcomes. We undertook a field study to evaluate the use of a whole blood creatinine/eGFR device to screen a rural Nicaraguan population to determine the variability between creatinine methods and specimen types. All specimens including capillary and venous dried blood spots (DBS) were tested with an isotope dilution liquid chromatography mass spectrometry (ID-LCMS) gold standard method. This is to our knowledge the first time a capillary whole blood (POC) method has been directly compared to the gold standard IDMS method, through the novel approach of using dried blood spots. Capillary and venous whole blood specimens were obtained and tested directly with the BCMS method, and then, DBS samples were prepared. Venous plasma specimens were tested using three laboratory analyzer creatinine methods. DBS were sent to the site performing ID-LCMS. Control samples were also prepared to assess the stability of shipment and storage of DBS. The ID-LCMS method was aligned using primary and secondary standards. Sixty-six (66) patients participated in the study, and the CKD prevalence rate was 7.8%. While all creatinine methods showed a good correlation to ID-LCMS, there was a positive bias (mean absolute bias range: 0.21-0.63 mg/dL). All methods used were 100% sensitive, but specificity varied from 62.7 to 94.9% with PPV ranging from 25 to 62.5%. A correction factor was used to align the values from each method to ID-LCMS which improved the specificity of each method. This study used a unique DBS approach to align capillary whole blood creatinine to ID-LCMS. To ensure reliability of BCMS for identifying screened patients with CKD, it is important to establish IDMS traceability and alignment prior to undertaking CKD studies.

Bedside Glucose Monitoring-Is it Safe? A New, Regulatory-Compliant Risk Assessment Evaluation Protocol in Critically Ill Patient Care Settings.

OBJECTIVES: New data have emerged from ambulatory and acute care settings about adverse patient events, including death, attributable to erroneous blood glucose meter measurements and leading to questions over their use in critically ill patients. The U.S. Food and Drug Administration published new, more stringent guidelines for glucose meter manufacturers to evaluate the performance of blood glucose meters in critically ill patient settings. The primary objective of this international, multicenter, multidisciplinary clinical study was to develop and apply a rigorous clinical accuracy assessment algorithm, using four distinct statistical tools, to evaluate the clinical accuracy of a blood glucose monitoring system in critically ill patients. DESIGN: Observational study. SETTING: Five international medical and surgical ICUs. PATIENTS: All patients admitted to critical care settings in the centers. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Glucose measurements were performed on 1,698 critically ill patients with 257 different clinical conditions and complex treatment regimens. The clinical accuracy assessment algorithm comprised four statistical tools to assess the performance of the study blood glucose monitoring system compared with laboratory reference methods traceable to a definitive standard. Based on POCT12-A3, the Clinical Laboratory Standards Institute standard for hospitals about hospital glucose meter procedures and performance, and Parkes error grid clinical accuracy performance criteria, no clinically significant differences were observed due to patient condition or therapy, with 96.1% and 99.3% glucose results meeting the respective criteria. Stratified sensitivity and specificity analysis (10 mg/dL glucose intervals, 50-150 mg/dL) demonstrated high sensitivity (mean = 95.2%, SD = ± 0.02) and specificity (mean = 95. 8%, SD = ± 0.03). Monte Carlo simulation modeling of the study blood glucose monitoring system showed low probability of category 2 and category 3 insulin dosing error, category 2 = 2.3% (41/1,815) and category 3 = 1.8% (32/1,815), respectively. Patient trend analysis demonstrated 99.1% (223/225) concordance in characterizing hypoglycemic patients. CONCLUSIONS: The multicomponent, clinical accuracy assessment algorithm demonstrated that the blood glucose monitoring system was acceptable for use in critically ill patient settings when compared to the central laboratory reference method. This clinical accuracy assessment algorithm is an effective tool for comprehensively assessing the validity of whole blood glucose measurement in critically ill patient care settings.