Analytical quality of near-patient blood cholesterol and glucose determinations.
BACKGROUND
Screening for diabetes and hypercholesterolemia is widely advocated, and extra-laboratory testing could play a major role in cost-effective population screening. We wished to assess the analytical quality and interchangeability of capillary blood cholesterol and glucose assays as performed 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 interchangeability in routine use, six volunteers visited each of 12 randomly selected pharmacies consecutively during a 3-week period to have their fasting blood glucose and cholesterol concentrations determined. For comparison purposes, a similar procedure was followed to evaluate the eight clinical chemistry laboratories 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 variation (11% vs 6.1% for cholesterol; 10% vs 7.6% for glucose). For glucose measurements, near-patient testing in pharmacies demonstrated a bias of -48.1% 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 with -10.6% to 3.7% in laboratories. The percentage of closeness to the homeostatic 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 blood analyses under ideal conditions, performance goals often are not achieved in practice as indicated by a higher uncertainty of cholesterol and glucose blood results when determined in pharmacies. Nonuniformity of calibration procedures, deficiencies in training, a lack of internal quality control, and the absence of an external quality assessment program may all contribute to the current state of affairs.
Department of Chemical Pathology, University of Pretoria, Institute of Pathology, PO Box 2034, Pretoria 0001, South Africa. mdupless@medic.up.ac.za
M
M
du Plessis
J B
JB
Ubbink
W J
WJ
Vermaak
D001786:Blood Glucose / Q000032:analysis*; D002784:Cholesterol / Q000097:blood* / Q000592:standards; D005947:Glucose / Q000592:standards; D006801:Humans; D019095:Point-of-Care Systems; D011786:Quality Control; D011933:Reagent Kits, Diagnostic; D012015:Reference Standards
D001786:Blood Glucose; D011933:Reagent Kits, Diagnostic; D002784:Cholesterol; D005947:Glucose