Third Department of Dermatology, A. Sygros Hospital, Semitelou 6, Athens, Greece.
Dermatology. 2010;221 Suppl 1:43-7. doi: 10.1159/000316184. Epub 2010 Aug 9.
Psoriasis affects about 2-3% of the Caucasian population. Biologics such as infliximab, etanercept, adalimumab and ustekinumab are efficacious treatments of plaque-type psoriasis. Critical to monitoring drug efficacy and safety is availability of long-term data. Despite the chronic nature of psoriasis, to date limited long-term clinical data have been available, as challenges are inherent in conducting a long-term analysis. With increasing time, it is more likely that the number of patients discontinuing treatment will also increase, due to loss of efficacy, adverse events or loss to follow-up. Interpretation of these data becomes confounded when one must consider missing data. Several approaches to analysing long-term data exist, and each accounts for missing data differently.
To demonstrate that the choice of a particular analysis method to account for missing data has great impact on the assessed response rate.
We used data from an open-label study over 3 years of continuous treatment with infliximab in patients with plaque-type psoriasis. These data were analysed by three methods--last observation carried forward, observed values and non-responder imputation--to account for missing data.
The 3-year PASI 75 responses varied from 41 to 75%, depending on the method of analysis; this shows that the response rate can almost double when a more liberal analytical approach is used.
While it is clear that the need for long-term data on biologics in psoriasis is great, considering the analysis undertaken is important when designing long-term studies and interpreting the resulting data. When analysis methods such as observed values only or last observation carried forward are used, the results of the more conservative non-responder imputation should also be presented to give a fair overview of the long-term efficacy of a treatment for plaque-type psoriasis.
银屑病影响约 2-3%的白种人。英夫利昔单抗、依那西普、阿达木单抗和乌司奴单抗等生物制剂是斑块型银屑病的有效治疗方法。监测药物疗效和安全性的关键是获得长期数据。尽管银屑病具有慢性性质，但迄今为止，由于长期分析中存在固有挑战，可用的长期临床数据有限。随着时间的推移，由于疗效丧失、不良反应或失访，停止治疗的患者数量也可能增加。当必须考虑缺失数据时，这些数据的解释变得复杂。目前存在几种分析长期数据的方法，每种方法对缺失数据的处理方式都不同。
证明选择特定的分析方法来处理缺失数据对评估的响应率有很大影响。
我们使用了一项为期 3 年的开放性研究中连续使用英夫利昔单抗治疗斑块型银屑病患者的 3 年数据。这些数据通过三种方法进行分析，即最后观察值结转、观察值和无应答者插补，以处理缺失数据。
3 年 PASI75 反应率因分析方法而异，范围为 41-75%；这表明，当使用更宽松的分析方法时，反应率几乎可以翻倍。
虽然很明显需要长期的生物制剂治疗银屑病的数据，但在设计长期研究和解释结果时，考虑所进行的分析非常重要。当仅使用观察值或最后观察值结转等分析方法时，还应呈现更保守的无应答者插补的结果，以公正地概述斑块型银屑病治疗的长期疗效。
