Neumann N J, Hölzle E, Plewig G, Schwarz T, Panizzon R G, Breit R, Ruzicka T, Lehmann P
Department of Dermatology, Heinrich-Heine-University, Duesseldorf, Germany.
J Am Acad Dermatol. 2000 Feb;42(2 Pt 1):183-92. doi: 10.1016/s0190-9622(00)90124-5.
In 1984, the German, Austrian, and Swiss Photopatch Test Group was founded to standardize the photopatch test procedure and to investigate photoallergic reactions, as well as the epidemiology of photoallergy, in central Europe. Therefore in a first test period from 1985-1990, 32 test substances were applied on the backs of patients suspected to be photosensitive. After evaluation of these data, some substances were dismissed, and others were additionally integrated into the test tray. Thus a modified test tray comprising 26 test substances was used for the second test period (1991-1997).
According to the standard photopatch test procedure defined in the first test period, the aim of this multicenter study was to apply compounds from the modified second test tray to a large group of photosensitive patients. After evaluation of the second test period (1991-1997), the outcome was compared with the results of the first period. On the basis of these results and influenced by concurrently published case reports, a third modified photopatch test tray has been established.
After the application of a duplicate test tray for 24 hours, one test site was irradiated with 10 J/cm(2) UVA, and the other test site served as the control area. Readings were performed immediately and 24, 48, and 72 hours after irradiation. Test reactions were qualitatively graded according to a 4-point scale and classified by the investigators of the participating centers. In 49 participating clinics 1261 photopatch tests were performed. All data were subjected to computer-assisted analysis by using a specially developed software to classify all positive test reactions as plain contact or photoinduced reactions (nonspecific, toxic, or allergic photoreactions) and to define substance-specific reaction patterns.
In test period 1 data of 1129 patients were evaluated. From 2859 positive test reactions, 28.6% were excluded as plain contact reactions, 71.4% were found to be photoinduced reactions, and 3.8% were classified as photoallergic. In test period 2 data of 1261 patients were evaluated. One thousand four hundred fifteen positive test reactions were observed, and of these, 28.7% were excluded as plain contact reactions, 71.3% were classified as photoinduced reactions, and 8.1% were classified as photoallergic reactions. In both test periods nonsteroidal anti-inflammatory drugs, disinfectants, and phenothiazines represented the leading photoallergens in the evaluated central European region. By using computer-assisted reaction pattern analysis, substance-specific reaction patterns could be distinguished. These substance-specific reaction patterns comprised 4 main categories: the well-known decrescendo (phototoxic) and crescendo (photoallergic) reaction patterns, as well as a combined and a plateau pattern.
The test modification after the first test period led to a notably reduced number of positive (mainly nonphotoallergic and thus nonrelevant) test reactions per patient in the second test period (from 2.6 to 1.1). In contrast, the percentage of photoallergic reactions increased significantly from 3.8% to 8.1% of all positive test reactions. Test modifications after the first test period led to a remarkably improved specificity of the photopatch test. Furthermore, substance-specific reaction patterns observed in test period 1 were confirmed in test period 2.
1984年，德国、奥地利和瑞士光斑贴试验小组成立，旨在规范光斑贴试验程序，并调查中欧地区的光过敏反应以及光过敏的流行病学情况。因此，在1985年至1990年的第一个试验阶段，将32种试验物质应用于疑似光敏患者的背部。在对这些数据进行评估后，一些物质被剔除，其他物质则被额外纳入试验盘。于是，在第二个试验阶段（1991年至1997年）使用了包含26种试验物质的改良试验盘。
根据第一个试验阶段定义的标准光斑贴试验程序，这项多中心研究的目的是将改良后的第二个试验盘中的化合物应用于一大群光敏患者。在对第二个试验阶段（1991年至1997年）的数据进行评估后，将结果与第一阶段的结果进行比较。基于这些结果并受同期发表的病例报告影响，已建立了第三个改良光斑贴试验盘。
在应用重复试验盘24小时后，一个试验部位接受10 J/cm²的UVA照射，另一个试验部位作为对照区域。在照射后立即以及24、48和72小时进行读数。试验反应根据4级评分进行定性分级，并由参与中心的研究人员进行分类。在49个参与诊所共进行了1261次光斑贴试验。所有数据通过使用专门开发的软件进行计算机辅助分析，以将所有阳性试验反应分类为单纯接触性或光诱导反应（非特异性、毒性或过敏性光反应），并确定物质特异性反应模式。
在试验阶段1，对1129例患者的数据进行了评估。在2859次阳性试验反应中（排除单纯接触性反应），28.6%被排除为单纯接触性反应，71.4%被发现是光诱导反应，3.8%被分类为光过敏反应。在试验阶段2，对1261例患者的数据进行了评估。观察到1415次阳性试验反应，其中28.7%被排除为单纯接触性反应，71.3%被分类为光诱导反应，8.1%被分类为光过敏反应。在两个试验阶段，非甾体抗炎药、消毒剂和吩噻嗪类药物是中欧地区评估的主要光过敏原。通过计算机辅助反应模式分析，可以区分物质特异性反应模式。这些物质特异性反应模式包括4个主要类别：众所周知的递减（光毒性）和递增（光过敏）反应模式，以及组合模式和平原模式。
第一个试验阶段后的试验改良导致第二个试验阶段每位患者的阳性（主要是非光过敏且因此不相关的）试验反应数量显著减少（从2.6降至1.1）。相比之下，光过敏反应的百分比从所有阳性试验反应的3.8%显著增加到8.1%。第一个试验阶段后的试验改良导致光斑贴试验的特异性显著提高。此外，试验阶段1中观察到的物质特异性反应模式在试验阶段2中得到了证实。
