Using Patient-Level Data from Psoriasis Clinical Trials to Evaluate the Quantitative Relationship between Changes in Skin and Nail Psoriasis

Psoriasis is a chronic (long-lasting) disease in which skin cells grow too quickly. Patches of skin become rough and red, most often on the scalp, elbows, or knees, but in other parts of the body also. About half of patients with psoriasis have psoriasis in their nails (nail psoriasis). Nail psoriasis changes fingernails and toenails, causing pitting, whitening, bleeding, discoloration, dryness, thickening of the skin beneath the nail, loosening, separation, and crumbling. About 11 million people in the United States have psoriasis, and about 4.7 million people in the United States have nail psoriasis. Nobody knows why only some patients with psoriasis get nail psoriasis, nobody knows why some patients have mild skin psoriasis and severe nail psoriasis (or the other way around), and nobody knows whether all medicines that improve skin psoriasis also improve nail psoriasis. In other words, nobody knows how closely these different types of psoriasis are connected. Systemic therapies are treatments using substances that travel through the bloodstream, reaching and affecting cells all over the body. There are many systemic therapies that improve skin psoriasis and nail psoriasis. We want to learn if, when skin psoriasis improves, is it possible to predict how much nail psoriasis will improve no matter what type of systemic therapy is used. The other possibility is that some types of systemic therapy work better for skin psoriasis than nail psoriasis, or the other way around. The value of learning the answer is that it may help health care providers and psoriasis patients decide which systemic therapy to choose, in part based on how bad the skin and nail psoriasis is in each individual. We will look at data from studies comparing two different systemic therapies. For each patient with skin and nail psoriasis, we will see how much each therapy improved skin psoriasis, and how much each therapy improved nail psoriasis. We will check if how much skin psoriasis and nail psoriasis improved was different between the two therapies.

银屑病（Psoriasis）是一类慢性迁延性疾病，患者皮肤细胞增殖速率异常加快。患者皮肤会出现粗糙发红的斑块，好发于头皮、肘部或膝盖，也可累及身体其他部位。约半数银屑病患者会并发甲银屑病（Nail Psoriasis）。甲银屑病会累及手指甲和脚趾甲，引发甲凹点、甲白点、甲下出血、甲变色、甲干燥、甲下皮肤增厚、甲松动、甲剥离以及甲碎屑等病变。美国约有1100万银屑病患者，其中甲银屑病患者约470万。目前学界尚未明确为何仅部分银屑病患者会并发甲银屑病；也不清楚为何部分患者仅表现为轻度皮肤银屑病却伴随重度甲银屑病，反之亦然；更无法确定所有改善皮肤银屑病的药物是否同样对甲银屑病有效。换言之，学界尚未明确这两类银屑病之间的关联紧密程度。系统性治疗（Systemic Therapies）是指通过血液循环将药物输送至全身各处细胞以发挥治疗作用的疗法。目前已有多种系统性治疗手段可同时改善皮肤银屑病与甲银屑病症状。本研究旨在明确：当患者的皮肤银屑病症状得到改善时，无论采用何种系统性治疗方案，是否均可通过该变化预测甲银屑病的改善程度。另一种可能性则是，部分系统性治疗方案对皮肤银屑病的改善效果优于甲银屑病，反之亦然。明确上述问题的研究价值在于，可帮助临床医护人员与银屑病患者根据每位患者皮肤与甲银屑病的严重程度，更合理地选择系统性治疗方案。本研究将纳入对比两种不同系统性治疗方案的临床研究数据。针对同时罹患皮肤银屑病与甲银屑病的患者，我们将评估每种治疗方案对其皮肤银屑病及甲银屑病的改善幅度。最终将对比两种治疗方案下，患者皮肤银屑病与甲银屑病的改善幅度是否存在差异。