Weissfeld J L, Holloway J J
Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA 15261.
J Clin Epidemiol. 1992 Sep;45(9):971-84. doi: 10.1016/0895-4356(92)90113-2.
Imprecise blood cholesterol measurement can be expected to adversely affect large scale efforts to detect and treat high blood cholesterol. Using protocols specified by the National Cholesterol Education Program (NCEP), we used computer simulation techniques to quantify the effects of blood cholesterol measurement variability on misclassification rates, costs, effectiveness, and cost-effectiveness of high blood cholesterol case-finding and treatment. At the time of initial case-finding, increased measurement variability was associated with a moderate decrease in the proportions assigned to a treatment state and in the positive predictive value of such an assignment. After 10 years of continual case-finding and treatment, measurement variability dramatically affected proportions assigned to drug treatment and diminished the percent on drugs with blood cholesterol levels truly above NCEP cutpoints. Extreme variability in blood cholesterol measurement increased per capita costs by 14-18% and diminished cost-effectiveness by at least 11-12%. The adverse effects of measurement variability on cost-effectiveness were much more pronounced if adjustments to life-expectancy were made to recognize the lower quality of life associated with drug treatment. Misclassification rates can be decreased and cost-effectiveness improved by performing repeated measurements of blood cholesterol before increasing intensity of treatment. Improvement in the precision of measurement are especially beneficial for low-risk individuals.
不准确的血液胆固醇测量可能会对检测和治疗高血胆固醇的大规模工作产生不利影响。我们采用美国国家胆固醇教育计划（NCEP）规定的方案，运用计算机模拟技术来量化血液胆固醇测量变异性对高血胆固醇病例发现及治疗的错误分类率、成本、效果和成本效益的影响。在初次病例发现时，测量变异性增加与分配到治疗状态的比例以及该分配的阳性预测值适度下降相关。经过10年的持续病例发现和治疗，测量变异性对分配到药物治疗的比例产生了显著影响，并降低了血液胆固醇水平真正高于NCEP切点的服药者百分比。血液胆固醇测量的极端变异性使人均成本增加了14 - 18%，并使成本效益降低了至少11 - 12%。如果对预期寿命进行调整以认识到与药物治疗相关的较低生活质量，那么测量变异性对成本效益的不利影响会更加明显。在增加治疗强度之前对血液胆固醇进行重复测量，可以降低错误分类率并提高成本效益。测量精度的提高对低风险个体尤其有益。
