Nepper-Christensen Steen, Backer Vibeke, DuBuske Lawrence M, Nolte Hendrik
Asthma and Allergy Unit, Department of Internal Medicine, Bispebjerg University Hospital, Copenhagen, Denmark.
Allergy Asthma Proc. 2003 Jul-Aug;24(4):253-8.
For the diagnosis of allergy, presence of allergen-specific immunoglobulin E (IgE) usually is established either by allergen skin tests or by in vitro allergen-specific IgE measurements. However, in vitro assays of specific IgE often are modified as manufacturers improve allergens or change reagents to optimize test performance, affecting the diagnostic performance of in vitro allergen-specific IgE assays. This investigation compares the diagnostic outcomes of the Hitachi Chemical Diagnostics chemiluminescent assay (CLA) and Pharmacia, capsulated hydrophilic carrier polymer (CAP) in vitro allergen-specific IgE test methods in patients with inhalant allergy to a panel of selected allergens. Sera were obtained from 60 consecutive patients who had a clinical history suggesting inhalant allergy and were evaluated by allergen skin-prick test (SPT). Only patients with clinical findings of allergic asthma or rhinoconjunctivitis were included. Sera from patients with at least one positive SPT, which clinically correlated with the case history, were used for specific IgE measurements. Sensitivity and specificity were defined as conditional probabilities describing performances of the CAP system and the CLA system in reference to a standard composed of a combination of allergen-specific symptoms and a positive SPT. A test concordance of 79% was found between the CLA and CAP test results with a correlation coefficient of 0.8. Allergen-specific IgE assay sensitivity of the CLA and CAP systems was similar and allergen dependent, ranging from 67 to 100%. Assay specificity ranged from 39 to 86% for the CLA system and from 36 to 81% for the CAP system. When comparing the specific IgE results with allergen SPTs, 75% (+/- 3%) of CLApositive patients had a positive SPT, and 92% (+/- 4%) of CAPpositive patients had a positive SPT. Eighty-four percent (+/- 4%) of CLAnegative patients had a negative SPT, whereas 69% (+/- 5%) of CAPnegative patients had a negative SPT. The overall concordance between skin tests and in vitro tests was 76% for CLA and 67% for CAP. CLA and CAP score values showed good correlation and both tests may be useful when skin tests cannot be performed to identify subjects with IgE-mediated allergy. The CLA and CAP assays for allergen-specific IgE may be useful as part of an initial allergy evaluation because of the high negative predictive value of negative test results. For the majority of allergens the sensitivity was high. However, the specificity of both in vitro tests was low, indicating that positive in vitro test results should be evaluated carefully in conjunction with clinical symptoms and allergen-specific skin tests to determine the clinical relevance of the allergen sensitization.
对于过敏的诊断，通常通过变应原皮肤试验或体外变应原特异性免疫球蛋白E（IgE）检测来确定是否存在变应原特异性IgE。然而，随着制造商改进变应原或更换试剂以优化检测性能，特异性IgE的体外检测方法常常会被修改，这会影响体外变应原特异性IgE检测的诊断性能。本研究比较了日立化学诊断公司的化学发光免疫分析法（CLA）和法玛西亚公司的包被亲水性载体聚合物（CAP）体外变应原特异性IgE检测方法，用于对一组选定变应原吸入性过敏患者的诊断结果。连续从60例有提示吸入性过敏临床病史且经变应原皮肤点刺试验（SPT）评估的患者中获取血清。仅纳入有过敏性哮喘或鼻结膜炎临床表现的患者。来自至少一项与病史临床相关的阳性SPT患者的血清用于特异性IgE检测。敏感性和特异性被定义为描述CAP系统和CLA系统相对于由变应原特异性症状和阳性SPT组合构成的标准的检测性能的条件概率。CLA和CAP检测结果之间的检测一致性为79%，相关系数为0.8。CLA和CAP系统变应原特异性IgE检测的敏感性相似且依赖于变应原，范围为67%至100%。CLA系统的检测特异性范围为39%至&6%，CAP系统的检测特异性范围为36%至81%。当将特异性IgE结果与变应原SPT进行比较时，CLA阳性患者中有75%（±3%）的SPT为阳性，CAP阳性患者中有92%（±4%）的SPT为阳性。CLA阴性患者中有84%（±4%）的SPT为阴性，而CAP阴性患者中有69%（±5%）的SPT为阴性。皮肤试验和体外试验之间的总体一致性，CLA为76%，CAP为67%。CLA和CAP评分值显示出良好的相关性，当无法进行皮肤试验以识别IgE介导的过敏患者时，这两种检测方法可能都有用。CLA和CAP变应原特异性IgE检测由于阴性检测结果具有较高的阴性预测价值，可能作为初始过敏评估的一部分有用。对于大多数变应原，敏感性较高。然而，两种体外检测的特异性都较低，这表明体外检测阳性结果应结合临床症状和变应原特异性皮肤试验仔细评估，以确定变应原致敏的临床相关性。
