Understanding the Relationship Between Pruritus Severity and Work Productivity in Patients With Moderate-to-Severe Psoriasis: Sleep Problems Are a Mediating Factor.

BACKGROUND: Psoriasis is a debilitating skin disease associated with substantial pruritus, work impairment, and sleep disturbance. OBJECTIVE: This study evaluated associations between pruritus and work productivity, and the role of sleep problems as a possible mediator of the relationship between the two. METHODS AND MATERIALS: Data from a pruritus visual analog scale (Itch VAS), the Medical Outcomes Study Sleep Scale (MOS-SS), and the Work Productivity and Activity Impairment Questionnaire (WPAI) were collected in a phase 2 clinical trial in patients with psoriasis treated with ixekizumab or placebo. Mediating effects of sleep were tested in multiple regressions with pruritus severity (independent variable) and work productivity (dependent variable). Sobel tests evaluated the significance of sleep's effect. RESULTS: Several MOS-SS domains were significantly associated with the WPAI presenteeism, work productivity, and activity impairment scores, and decreased the effect of pruritus. Sobel tests indicated that the Sleep Problems Index I had a significant effect (P<.05) in mediating the relationship between pruritus and presenteeism, work productivity, and activity impairment. CONCLUSION: Sleep may mediate the role of pruritus on work productivity, but both factors appear to have independent negative effects on work.

Prevalence and incidence rates of cardiovascular, autoimmune, and other diseases in patients with psoriatic or psoriatic arthritis: a retrospective study using Clinical Practice Research Datalink.

BACKGROUND: Previous studies have demonstrated that patients with psoriasis have higher rates of comorbidities compared to the general population. Despite the clinical and economic burden of psoriatic disease, there have been few large-scale observational studies focused on this condition. OBJECTIVE: To assess rates of cardiovascular, autoimmune, infectious and other conditions in patients with psoriasis or psoriatic arthritis (PSA). METHODS: The data for this retrospective study were obtained from the Clinical Practice Research Datalink (CRPD). Cohorts of patients with psoriasis (n = 27,672; mild, n = 22,174, severe, n = 5498) and PSA (n = 1952) were generated based on the diagnosis made by general practitioner or specialist recorded in CPRD between 2006 and 2010. Frequencies of comorbidities at baseline and incidence rate ratios (IRR) of medical conditions occurring during follow-up were calculated and compared between groups. Cox proportional hazard models were employed to compare hazard ratios (HR) of comorbidities across the same subpopulations previously described. RESULTS: Significant differences in the unadjusted risk of cardiovascular disease, hyperlipidaemia, diabetes, skin cancer and autoimmune diseases were observed between patients with differing severity of psoriasis or between PSA and psoriasis patients. The adjusted HR analyses confirmed patients with severe psoriasis had significantly higher rates of several conditions including diabetes (1.23; 95% CI: 1.01-1.51) and rheumatoid arthritis (2.88; 95% CI: 2.25-3.67) compared to patients with mild psoriasis. Patients with PSA had significantly higher adjusted rates of hypertension (1.30; 95% CI: 1.01-1.68), rheumatoid arthritis (6.93; 95% CI: 5.45-8.80) and ankylosing spondylitis (6.98; 95% CI: 2.37-20.58) compared to those with severe psoriasis. CONCLUSION: Patients with mild psoriasis are less affected by comorbid conditions than those with severe psoriasis, and patients with psoriasis are less affected by comorbidities than those with PSA. Given the differences observed across severities of psoriasis and between psoriasis and PSA, each patient subgroup should be taken into consideration in clinical practice and future research.

Itching is a significant problem and a mediator between disease severity and quality of life for patients with psoriasis: results from a randomized controlled trial.

BACKGROUND: 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. OBJECTIVES: To evaluate the role of pruritus (itch) in mediating the relationship between improvements in disease severity and HRQOL. METHODS: 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. RESULTS: Improvement in PASI was highly correlated with pruritus improvement and improvements in DLQI total and domain scores at week 16 (P < 0·01). Multiple hierarchical linear regression analyses showed a statistically significant (P < 0·01) 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 < 0·05) on the association of PASI improvement with improvement in DLQI total score and all domains except the personal relationships score. CONCLUSIONS: Pruritus appears to be an important mediator of the association between improvements in disease severity and HRQOL in patients with moderate-to-severe psoriasis.