Weatherley Beth D, Chambless Lloyd E, Heiss Gerardo, Catellier Diane J, Ellison Curtis R
Duke Clinical Research Institute, Duke University Medical Center, Durham, NC, USA.
BMC Cardiovasc Disord. 2006 Feb 21;6:7. doi: 10.1186/1471-2261-6-7.
A low ankle-brachial index (ABI) is associated with increased risk of coronary heart disease, stroke, and death. Regression model parameter estimates may be biased due to measurement error when the ABI is included as a predictor in regression models, but may be corrected if the reliability coefficient, R, is known. The R for the ABI computed from DINAMAP readings of the ankle and brachial SBP is not known.
A total of 119 participants in both the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) had repeat ABIs taken within 1 year, using a common protocol, automated oscillometric blood pressure measurement devices, and technician pool.
The estimated reliability coefficient for the ankle systolic blood pressure (SBP) was 0.68 (95% CI: 0.57, 0.77) and for the brachial SBP was 0.74 (95% CI: 0.62, 0.83). The reliability for the ABI based on single ankle and arm SBPs was 0.61 (95% CI: 0.50, 0.70) and the reliability of the ABI computed as the ratio of the average of two ankle SBPs to two arm SBPs was estimated from simulated data as 0.70.
These reliability estimates may be used to obtain unbiased parameter estimates if the ABI is included in regression models. Our results suggest the need for repeated measures of the ABI in clinical practice, preferably within visits and also over time, before diagnosing peripheral artery disease and before making therapeutic decisions.
低踝臂指数（ABI）与冠心病、中风和死亡风险增加相关。当ABI作为回归模型中的预测变量时，由于测量误差，回归模型参数估计可能存在偏差，但如果可靠性系数R已知，则可以进行校正。通过踝部和臂部收缩压（SBP）的DINAMAP读数计算出的ABI的R值尚不清楚。
社区动脉粥样硬化风险（ARIC）研究和美国国立心肺血液研究所家族心脏研究（FHS）中的119名参与者在1年内采用通用方案、自动振荡式血压测量设备和技术人员团队重复测量ABI。
踝部收缩压（SBP）的估计可靠性系数为0.68（95%置信区间：0.57，0.77），臂部SBP的估计可靠性系数为0.74（95%置信区间：0.62，0.83）。基于单次踝部和臂部SBP的ABI的可靠性为0.61（95%置信区间：0.50，0.70），通过模拟数据估计，将两个踝部SBP的平均值与两个臂部SBP的比值计算得出的ABI的可靠性为0.70。
如果将ABI纳入回归模型，这些可靠性估计值可用于获得无偏参数估计。我们的结果表明，在临床实践中，在诊断外周动脉疾病和做出治疗决策之前，需要重复测量ABI，最好在就诊期间以及随时间进行测量。
