Volles D F, McKenney J M, Miller W G, Ruffen D, Zhang D
Department of Pharmacy and Pharmaceutics, Medical College of Virginia, Virginia Commonwealth University, Richmond, USA.
Pharmacotherapy. 1998 Jan-Feb;18(1):184-92.
Several relatively inexpensive compact analyzers for measuring cholesterol are available for use outside of the clinical laboratory. We evaluated the analytic and clinical performance of total cholesterol assayed with the AccuMeter (ChemTrak) and the LDX (Cholestech). Accuracy of both devices was evaluated by collecting capillary and venous whole blood from 100 subjects and assaying for total cholesterol. Results were compared with the Centers for Disease Control standardized reference laboratory method. Mean percent bias, mean absolute percent bias, and percentage of subjects with total error above +/- 8.9% were calculated and results were compared with recommendations from National Cholesterol Education Program (NCEP) for total cholesterol measurements. Precision was evaluated by assay of three pooled serum samples with both devices in duplicate in two runs/day for 20 days. The CV for each serum pool for each device was calculated and compared with NCEP recommendations for precision for total cholesterol measurements. Results with the two devices were compared. The total cholesterol mean percent bias for capillary samples was 2.1% for the LDX and -1.0% for the AccuMeter (p<0.01), and for venous samples 1.6 and -2.0%, respectively (p<0.001). The mean absolute percent bias for capillary samples was 5.4 and 5.2%, respectively (p=0.29), and for venous samples was 5.0 and 5.7% (p=0.79). Each device had an excessive number (12-22%) of individual results that exceeded NCEP recommended total error for a single cholesterol measurement (+/- 8.9%). In the precision analysis the average CV from all three serum pools was 4.0% and 5.3% for the LDX and AccuMeter, respectively (p<0.05). Thus both devices failed to meet the NCEP recommendation for precision of 3% CV. They both provided total cholesterol results that correctly classified individual patients into appropriate risk groups 95% of the time or better if values within +/- 8.9% of NCEP cut points for risk classification were ignored. Both devices met the NCEP +/- 3% requirement for total cholesterol mean percent bias but did not meet the +/- 3% requirement for CV as a measure of precision. Because of the variability in results, both devices had excessive numbers of individual subjects with total cholesterol results greater than the recommended total error limit of +/- 8.9% difference from the standardized method. Despite variability in some individual results, the rate of clinical misclassifications for coronary heart disease risk was relatively low for both devices if results near the NCEP cut points were repeated.
有几种相对便宜的用于测量胆固醇的紧凑型分析仪可在临床实验室之外使用。我们评估了使用AccuMeter（ChemTrak）和LDX（Cholestech）测定总胆固醇的分析性能和临床性能。通过收集100名受试者的毛细血管血和静脉全血并测定总胆固醇来评估这两种设备的准确性。将结果与疾病控制中心的标准化参考实验室方法进行比较。计算平均偏差百分比、平均绝对偏差百分比以及总误差超过±8.9%的受试者百分比，并将结果与国家胆固醇教育计划（NCEP）关于总胆固醇测量的建议进行比较。通过在20天内每天两次对三个混合血清样本进行重复测定来评估精密度。计算每种设备对每个血清池的CV，并与NCEP关于总胆固醇测量精密度的建议进行比较。比较两种设备的结果。LDX对毛细血管样本的总胆固醇平均偏差百分比为2.1%，AccuMeter为-1.0%（p<0.01），对静脉样本分别为1.6%和-2.0%（p<0.001）。毛细血管样本的平均绝对偏差百分比分别为5.4%和5.2%（p=0.29），静脉样本为5.0%和5.7%（p=0.79）。每种设备都有过多（12 - 22%）的个体结果超过了NCEP推荐的单次胆固醇测量总误差（±8.9%）。在精密度分析中，LDX和AccuMeter对所有三个血清池的平均CV分别为4.0%和5.3%（p<0.05）。因此，两种设备均未达到NCEP推荐的3%CV精密度要求。如果忽略风险分类的NCEP切点±8.9%范围内的值，它们都能在95%或更高比例的情况下将个体患者正确分类到适当的风险组中。两种设备均满足NCEP对总胆固醇平均偏差百分比±3%的要求，但不满足作为精密度指标的CV±3%的要求。由于结果存在变异性，两种设备都有过多个体受试者的总胆固醇结果与标准化方法的差异大于推荐的总误差极限±8.9%。尽管一些个体结果存在变异性，但如果重复接近NCEP切点的结果，两种设备冠心病风险的临床错误分类率相对较低。
