Lock-Andersen J, Wulf H C
Department of Dermatology, National University Hospital, Rigshospitalet, Copenhagen, Denmark.
Photodermatol Photoimmunol Photomed. 1996 Aug;12(4):154-61. doi: 10.1111/j.1600-0781.1996.tb00192.x.
The ultraviolet (UV) sensitivity is determined by a phototest where the skin is exposed to well-defined doses of UV radiation and the resulting erythema is graded by visual scoring after 20-24 h. In this study we wanted to estimate the reproducibility of erythema assessment in phototesting. Twenty-one healthy Caucasians with skin types I to IV were phototested on UV un-exposed buttock skin using a xenon lamp solar simulator. Twenty-four hours after UV exposure eight physicians independently graded the erythema reactions two times. Data were analysed using inter- and intra-observer agreement and kappa statistics, which adjusts for agreement that could be caused by chance alone. Observed agreement and kappa statistics were found to decrease with increasing intensity of erythema and to be lower for skin types III and IV compared to skin types I and II. Intra-observer agreement was uniformly better than inter-observer agreement. The difference between observers assessment could be as much as three clinical erythema grades. Physicians's previous experience with phototesting only had a minor influence on agreement. In conclusion, phototesting is based on subjective assessment of erythema and is not as precise and reproducible as expected. Agreement was better for barely perceptible erythema than for erythema with a well-defined border and we therefore recommend that the barely perceptible erythema reaction should be used for measurement of the minimal erythema dose.
紫外线（UV）敏感性通过光试验来确定，即让皮肤暴露于明确剂量的紫外线辐射下，在20 - 24小时后通过视觉评分对产生的红斑进行分级。在本研究中，我们想评估光试验中红斑评估的可重复性。21名皮肤类型为I至IV型的健康白种人，使用氙灯太阳模拟器在未暴露于紫外线的臀部皮肤上进行光试验。紫外线照射24小时后，8名医生独立对红斑反应进行了两次分级。使用观察者间和观察者内一致性以及kappa统计分析数据，kappa统计可调整仅由偶然因素导致的一致性。观察到的一致性和kappa统计结果显示，随着红斑强度增加而降低，并且与I型和II型皮肤相比，III型和IV型皮肤的一致性更低。观察者内一致性始终优于观察者间一致性。观察者评估之间的差异可能高达三个临床红斑等级。医生以前的光试验经验对一致性仅有轻微影响。总之，光试验基于对红斑的主观评估，并不像预期的那样精确和可重复。对于几乎难以察觉的红斑，一致性优于边界清晰的红斑，因此我们建议使用几乎难以察觉的红斑反应来测量最小红斑剂量。
