Quality Indicators in Laboratory Medicine: from theory to practice. Preliminary data from the IFCC Working Group Project "Laboratory Errors and Patient Safety".

BACKGROUND: The adoption of Quality Indicators (QIs) has prompted the development of tools to measure and evaluate the quality and effectiveness of laboratory testing, first in the hospital setting and subsequently in ambulatory and other care settings. While Laboratory Medicine has an important role in the delivery of high-quality care, no consensus exists as yet on the use of QIs focussing on all steps of the laboratory total testing process (TTP), and further research in this area is required. METHODS: In order to reduce errors in laboratory testing, the IFCC Working Group on "Laboratory Errors and Patient Safety" (WG-LEPS) developed a series of Quality Indicators, specifically designed for clinical laboratories. In the first phase of the project, specific QIs for key processes of the TTP were identified, including all the pre-, intra- and post-analytic steps. The overall aim of the project is to create a common reporting system for clinical laboratories based on standardized data collection, and to define state-of-the-art and Quality Specifications (QSs) for each QI independent of: a) the size of organization and type of activities; b) the complexity of processes undertaken; and c) different degree of knowledge and ability of the staff. The aim of the present paper is to report the results collected from participating laboratories from February 2008 to December 2009 and to identify preliminary QSs. RESULTS AND CONCLUSIONS: The results demonstrate that a Model of Quality Indicators managed as an External Quality Assurance Program can serve as a tool to monitor and control the pre-, intra- and post-analytical activities. It might also allow clinical laboratories to identify risks that lead to errors resulting in patient harm: identification and design of practices that eliminate medical errors; the sharing of information and education of clinical and laboratory teams on practices that reduce or prevent errors; the monitoring and evaluation of improvement activities.

Diagnostic accuracy of the Triage D-dimer test for exclusion of venous thromboembolism in outpatients.

BACKGROUND: We evaluated the diagnostic performance of the Triage D-dimer test, a new fast quantitative point-of-care whole blood D-dimer assay and compared it with the Vidas D-dimer assay. MATERIALS AND METHODS: The study population comprised 319 outpatients for whom D-dimer testing was requested in order to rule out venous thromboembolism (VTE). Routine testing consisted of a plasma ELISA D-dimer analysis (Vidas). For all included patients, an additional EDTA whole blood D-dimer test (Triage) was performed. Patients were classified by reference imaging or by follow-up of the medical record. Accuracy indices, receiver operating characteristics and the kappa coefficient for agreement were calculated using the cutoff values recommended by the manufacturer. RESULTS: Prevalence of VTE was 14%. Sensitivity and specificity for VTE were 98% (95%CI: 88-100) and 34% (95%CI: 28-40) for Vidas and 91% (95%CI: 78-97) and 42% (95%CI: 36-48) for Triage, respectively. The differences in sensitivity and specificity between both D-dimer assays were statistically significant (McNemar, p<0.0001). ROC-curve analysis yielded an area under the curve of 0.83 (95%CI: 0.76-0.89) for the Vidas and 0.81 (95%CI: 0.74-0.88) for the Triage (p=0.396). The kappa coefficient for agreement between Vidas and Triage was 0.75 (95%CI: 0.68-0.79). CONCLUSIONS: The Triage and Vidas D-dimer tests show comparable diagnostic accuracy. Vidas showed a significant higher sensitivity. Our findings strongly suggest lowering the cutoff for the Triage D-dimer test from 400 to 350 ng/mL. In this way specificity lowers from 42 to 38%, but, more importantly, sensitivity increases from 91 to 95%.

Plasma-equivalent glucose at the point-of-care: evaluation of Roche Accu-Chek Inform and Abbott Precision PCx glucose meters.

BACKGROUND: Glucose testing at the bedside has become an integral part of the management strategy in diabetes and of the careful maintenance of normoglycemia in all patients in intensive care units. We evaluated two point-of-care glucometers for the determination of plasma-equivalent blood glucose. METHODS: The Precision PCx and the Accu-Chek Inform glucometers were evaluated. Imprecision and bias relative to the Vitros 950 system were determined using protocols of the Clinical Laboratory Standards Institute (CLSI). The effects of low, normal, and high hematocrit levels were investigated. Interference by maltose was also studied. RESULTS: Within-run precision for both instruments ranged from 2-5%. Total imprecision was less than 5% except for the Accu-Chek Inform at the low level (2.9 mmol/L). Both instruments correlated well with the comparison instrument and showed excellent recovery and linearity. Both systems reported at least 95% of their values within zone A of the Clarke Error Grid, and both fulfilled the CLSI quality criteria. The more stringent goals of the American Diabetes Association, however, were not reached. Both systems showed negative bias at high hematocrit levels. Maltose interfered with the glucose measurements on the Accu-Chek Inform but not on the Precision PCx. CONCLUSIONS: Both systems showed satisfactory imprecision and were reliable in reporting plasma-equivalent glucose concentrations. The most stringent performance goals were however not met.

Preliminary performance evaluation of blood gas analyzers.

BACKGROUND: We evaluated the imprecision and bias of three instruments for the determination of blood gases, pH and ionized calcium (Ca(2+)) in human arterial blood samples, in comparison with the performance of an established methodology. METHODS: The ABL 735, Omni S and Rapidpoint 405 blood gas analyzers were evaluated and compared to the ABL 620 analyzer. Imprecision was determined according to the NCCLS EP10-A2 evaluation protocol. The NCCLS EP9-A2 evaluation protocol was used to determine bias relative to the ABL 620 system. Experimental data were compared against preset quality specifications. RESULTS: The three new instruments showed excellent imprecision for the measurement of pH, but only the ABL 620 met the preset imprecision goals for all analytes tested. All new instruments showed good correlation with the comparative instrument. The slope of the regression equation was significantly different from 1.0 in six out of the 12 comparisons, indicating systematic differences between the instruments. Nevertheless, the predicted bias values relative to the comparative instrument did not exceed the preset quality specifications for two out of the three new instruments. CONCLUSIONS: Preliminary evaluation using the NCCLS evaluation protocols EP10-A2 and EP9-A2, may provide valuable information on performance characteristics of blood gas analyzers.