You will be given a definition of a task first, then some input of the task.
Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: In patients with moderate-to-severe psoriasis, health-related quality of life (HRQOL) has been shown to improve in parallel with improvement in disease severity.', 'To evaluate the role of pruritus (itch) in mediating the relationship between improvements in disease severity and HRQOL.', 'Data from a phase 2 clinical trial, in which 142 patients with moderate-to-severe plaque psoriasis received ixekizumab or placebo, were used for this posthoc analysis. Relationships between improvement in Psoriasis Area and Severity Index (PASI), Itch Visual Analogue Scale (VAS) and Dermatology Life Quality Index (DLQI), as well as in individual DLQI domains (symptoms and feelings, treatment, work and school, daily activities, leisure, and personal relationships) from baseline to week 16 were determined. Multiple hierarchical linear regressions and Sobel tests were conducted to evaluate the results.', 'Improvement in PASI was highly correlated with pruritus improvement and improvements in DLQI total and domain scores at week 16 (P<001). Multiple hierarchical linear regression analyses showed a statistically significant (P<001) association between improvement in pruritus and improvement in DLQI total score and each of the six DLQI domain scores after adjusting for improvement in PASI. Sobel tests indicated that pruritus had a significant mediation effect (P<005) on the association of PASI improvement with improvement in DLQI total score and all domains except the personal relationships score.
Answer: Pruritus appears to be an important mediator of the association between improvements in disease severity and HRQOL in patients with moderate-to-severe psoriasis.
Output:
Is itching a significant problem and a mediator between disease severity and quality of life for patients with psoriasis : results from a randomized controlled trial?