Haillot Annie, Pelland Andrée-Anne, Bossé Yohan, Carroll Tomás P, Maltais François, Dandurand Ronald J
Centre de Pneumologie, Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada.
Irish Centre for Genetic Lung Disease, Royal College of Surgeons in Ireland, Dublin, Ireland.
Chronic Obstr Pulm Dis. 2021 Oct 28;8(4):464-473. doi: 10.15326/jcopdf.2021.0228.
Measuring alpha-1 antitrypsin (AAT) serum levels is often the first step when investigating for alpha-1 antitrypsin deficiency (AATD). The purpose of this study was to determine the test-retest reproducibility of AAT serum levels and to determine if between-measurements variability was associated with acute phase markers of inflammation.
We retrospectively analyzed a sample of 255 patients from a community respirology practice with chronic obstructive pulmonary disease (COPD) in whom AAT serum levels were measured twice, on separate visits. White blood cell count and fibrinogen were also measured at the time of the second blood sampling as markers of acute phase inflammation. Intraclass correlation coefficient (ICC), Pearson correlation coefficient, and Bland-Altman analysis were used to document test-retest reproducibility. Regression analyses were used to identify potential correlates of test-retest AAT level differences.
Although the 2 AAT serum levels were significantly correlated, the between-measurement agreement was weak (ICC of 0.38 [95% confidence interval (CI), 0.27 to 0.48]; Pearson correlation coefficient of 0.34 [95% CI, 0.23 to 0.44]) and Bland-Altman analysis revealed wide 95% limits of agreement. Considering that an AAT serum level below 1.13g/L should trigger further investigations to confirm the AAT status, discrepancies between the test-retest AAT levels resulted in reconsidering requirement for further investigation in 22% of patients. A significant correlation between the fibrinogen value and the second AAT level was found (=0.21, =0.004 [=173]).
Serum AAT levels showed weak intra-individual reproducibility which could lead to AATD status misclassification and potentially a missed diagnosis of AATD.
在对α-1抗胰蛋白酶缺乏症（AATD）进行调查时，检测血清α-1抗胰蛋白酶（AAT）水平通常是第一步。本研究的目的是确定AAT血清水平的重测再现性，并确定测量间的变异性是否与炎症的急性期标志物相关。
我们回顾性分析了来自社区呼吸科诊所的255例慢性阻塞性肺疾病（COPD）患者的样本，这些患者的AAT血清水平在不同时间进行了两次测量。在第二次采血时还测量了白细胞计数和纤维蛋白原，作为急性期炎症的标志物。组内相关系数（ICC）、Pearson相关系数和Bland-Altman分析用于记录重测再现性。回归分析用于确定重测AAT水平差异的潜在相关因素。
尽管两次AAT血清水平显著相关，但测量间的一致性较弱（ICC为0.38[95%置信区间（CI），0.27至0.48]；Pearson相关系数为0.34[95%CI，0.23至0.44]），Bland-Altman分析显示一致性界限较宽。考虑到AAT血清水平低于1.13g/L应引发进一步检查以确认AAT状态，重测AAT水平之间的差异导致22%的患者重新考虑进一步检查的必要性。发现纤维蛋白原值与第二次AAT水平之间存在显著相关性（=0.21，=0.004[=173]）。
血清AAT水平显示出较弱的个体内再现性，这可能导致AATD状态的错误分类，并可能导致AATD的漏诊。
