Lane Michael B, Flatland Bente, Olin Shelly J, Fecteau Kellie A, Rick Markus, Giori Luca
J Am Vet Med Assoc. 2018 Dec 15;253(12):1580-1588. doi: 10.2460/javma.253.12.1580.
OBJECTIVE To investigate the precision of an ELISA for measurement of serum cortisol concentration (SCC) in dogs, assess agreement between this ELISA and 2 validated chemiluminescence assays (CLAs), and evaluate the clinical implications of any bias associated with this ELISA when measuring SCC in dogs. DESIGN Evaluation study. SAMPLE 75 stored, frozen serum samples from client-owned dogs. PROCEDURES Enzyme-linked immunosorbent assay precision was evaluated by measuring SCC of pooled serum samples. Agreement with standard methods was evaluated with Spearman rank correlation, Passing-Bablok regression, and Bland-Altman analysis to compare SCCs obtained with the ELISA and the 2 CLAs. An error grid was used to evaluate identified bias. RESULTS Within-laboratory coefficients of variation for pooled serum samples with low, medium, and high SCCs were 21.4%, 28.9%, and 13.0%, respectively. There was a high correlation between ELISA results (for all samples combined) and results of the 2 CLAs (CLA 1, r = 0.96; CLA 2, r = 0.97), but constant and proportional biases between the ELISA and CLAs were present at all concentrations. Clinically important disagreement between ELISA results and CLA results occurred in 16 of 63 (25%) samples, particularly with low and high SCCs. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the rate of clinical disagreement between the ELISA and CLAs was sufficiently high to recommend that equivocal results obtained with the ELISA be confirmed by a reference laboratory. Further evaluation of analytic performance of the ELISA should focus on samples with very high and very low SCCs.
目的 研究一种用于测量犬血清皮质醇浓度（SCC）的酶联免疫吸附测定（ELISA）的精密度，评估该ELISA与2种经过验证的化学发光测定法（CLA）之间的一致性，并评估在测量犬SCC时该ELISA相关偏差的临床意义。 设计 评估研究。 样本 来自客户拥有犬的75份储存的冷冻血清样本。 方法 通过测量混合血清样本的SCC评估酶联免疫吸附测定的精密度。采用Spearman秩相关、Passing-Bablok回归和Bland-Altman分析评估与标准方法的一致性，以比较ELISA和2种CLA获得的SCC。使用误差网格评估识别出的偏差。 结果 低、中、高SCC混合血清样本的实验室内变异系数分别为21.4%、28.9%和13.0%。ELISA结果（所有样本合并）与2种CLA结果（CLA 1，r = 0.96；CLA 2，r = 0.97）之间存在高度相关性，但ELISA和CLA之间在所有浓度下均存在恒定和比例偏差。ELISA结果与CLA结果在临床上的重要差异出现在63个样本中的16个（25%），特别是在低和高SCC时。 结论及临床意义 结果表明，ELISA与CLA之间临床差异的发生率足够高，建议ELISA获得的可疑结果由参考实验室进行确认。ELISA分析性能的进一步评估应集中在SCC非常高和非常低的样本上。
