Analytical quality of near-patient blood cholesterol and glucose determinations

Background: Screening for diabetes and hypercholesterolemia is widely advoc ated, and extra-laboratory testing could play a major role in cost-effectiv e population screening. We wished to assess the analytical quality and inte rchangeability of capillary blood cholesterol and glucose assays as perform ed on near-patient devices in pharmacies in Pretoria, South Africa. Methods: Accuracy of near-patient and laboratory analyzers was assessed by analyses of human-serum-based reference material. To assess interchangeabil ity in routine use, six volunteers visited each of 12 randomly selected pha rmacies consecutively during a 3-week period to have their fasting blood gl ucose and cholesterol concentrations determined. For comparison purposes, a similar procedure was followed to evaluate the eight clinical chemistry la boratories servicing Pretoria and surroundings. Results: The analytical performances in our laboratory of a single point-of -care instrument and of a laboratory analyzer compared well. Nevertheless, between-pharmacy analytical variation was larger than between-laboratory va riation (11% vs 6.1% for cholesterol; 10% vs 7.6% for glucose). For glucose measurements, near-patient testing in pharmacies demonstrated a bias of -4 8.1% to 16.2%, whereas bias for laboratory measurements was -1.0% to 7.4%. Cholesterol assays showed a bias of -5.6% to 16.6% in pharmacies compared w ith -10.6% to 3.7% in laboratories. The percentage of closeness to the home ostatic set point for a single glucose and cholesterol. determination done in any pharmacy was 24.6% and 23.6%, respectively. The corresponding values for laboratories were 16.9% and 15.6%, respectively. Conclusions: Although modern point-of-care instruments allow high-quality b lood analyses under ideal conditions, performance goals often are not achie ved in practice as indicated by a higher uncertainty of cholesterol and glu cose blood results when determined in pharmacies. Nonuniformity of calibrat ion procedures, deficiencies in training, a lack of internal quality contro l, and the absence of an external quality assessment program may all contri bute to the current state of affairs. (C) 2000 American Association for Cli nical Chemistry.