Speechley M, McNair S, Leffley A, Bass M
Department of Physical Therapy, Faculty of Applied Health Sciences, University of Western Ontario, London.
Can Fam Physician. 1995 Feb;41:240-5.
To compare the use of one and two blood samples for diagnosing hypercholesterolemia
A test-retest substudy conducted as part of a randomized control trial designed to compare the effectiveness of different counseling strategies for lowering serum cholesterol, dietary fat, and dietary cholesterol in patients with moderate hypercholesterolemia.
Thirty urban family practices.
One hundred forty-two patients provided two blood samples for total cholesterol (TC) level determination at two different times (test results were being used as an eligibility criterion for enrollment in the main trial).
Number of subjects correctly classified to cholesterol risk category (normal < 6.2 mmol/L; moderate 6.2 to 6.9 mmol/L; high > 6.9 mmol/L) on the basis of one TC value and on the average of two TC values.
Overall misclassification rate on initial TC level was 22.5%. Overall false-positive rate was 19.0%, but false-positive rate for those initially assigned to the high category was 50%. Overall false-negative rate was 3.5%. Misclassification rates did not differ statistically on the basis of age, sex, blood pressure, smoking status, family history of coronary heart disease, presence of diabetes, obesity, the laboratory used, or whether the patient had fasted before giving blood.
Single TC levels are too unreliable for diagnostic purposes, even if the subjects fast before testing. Family physicians should base their treatment decisions on the average of two cholesterol readings taken at different times 1 to 8 weeks apart.
比较使用一份血样和两份血样诊断高胆固醇血症的情况
作为一项随机对照试验的重测子研究，该随机对照试验旨在比较不同咨询策略对中度高胆固醇血症患者降低血清胆固醇、膳食脂肪和膳食胆固醇的效果。
30个城市家庭医疗诊所
142名患者在两个不同时间提供两份血样用于总胆固醇（TC）水平测定（检测结果用作主要试验入组的合格标准）。
根据一个TC值和两个TC值的平均值，正确分类到胆固醇风险类别的受试者数量（正常<6.2 mmol/L；中度6.2至6.9 mmol/L；高>6.9 mmol/L）。
初始TC水平的总体错误分类率为22.5%。总体假阳性率为19.0%，但最初被归为高风险类别的患者假阳性率为50%。总体假阴性率为3.5%。错误分类率在年龄、性别、血压、吸烟状况、冠心病家族史、糖尿病的存在、肥胖、所使用的实验室或患者采血前是否禁食等方面无统计学差异。
即使受试者在检测前禁食，单次TC水平用于诊断也过于不可靠。家庭医生应根据在相隔1至8周的不同时间采集的两次胆固醇读数的平均值来做出治疗决策。
