Roeback J R, Cook J R, Guess H A, Heyse J F
Department of Epidemiology, University of North Carolina, Chapel Hill 27599-7400.
J Clin Epidemiol. 1993 Oct;46(10):1159-71. doi: 10.1016/0895-4356(93)90115-h.
Intraindividual variability (IIV) in total cholesterol levels based on measurements taken 1 week apart is compared with an estimate based on measurements taken 2 years apart. Single-subject 95% confidence intervals around the mean of two repeated measurements were Xi +/- 21 and +/- 28 mg/dl, respectively, and Xi +/- 30 and +/- 40 mg/dl for a single measurement. Comparing these results with published estimates over varying time intervals shows a trend of decreasing IIV with shorter intervals, suggesting that confidence interval widths based on short-term repeated measurements and those based on longer-term repeated measurements may differ more than previously assumed. The practical consequences are that: (1) the level of misclassification inherent in the National Cholesterol Education Program (NCEP) guidelines may be less than had been estimated; and (2) reliable cholesterol reductions resulting from dietary or other interventions may be somewhat easier to detect. These findings have implications for the cost-effectiveness of cholesterol screening strategies and interventions to reduce cholesterol.
将基于相隔1周测量的总胆固醇水平的个体内变异性（IIV）与基于相隔2年测量的估计值进行比较。两次重复测量均值周围的单受试者95%置信区间分别为Xi±21和±28mg/dl，单次测量时为Xi±30和±40mg/dl。将这些结果与不同时间间隔公布的估计值进行比较，结果显示间隔越短，IIV呈下降趋势，这表明基于短期重复测量的置信区间宽度与基于长期重复测量的置信区间宽度之间的差异可能比之前设想的更大。实际影响在于：（1）美国国家胆固醇教育计划（NCEP）指南中固有的错误分类水平可能低于此前估计；（2）饮食或其他干预措施导致的可靠胆固醇降低可能更容易检测到。这些发现对胆固醇筛查策略和降低胆固醇干预措施的成本效益具有启示意义。
