Study Summary: Impact of Psoriasis Severity on Patient-Reported Health Outcomes

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The severity of psoriasis is related to the impact of the disease on patients’ quality of life. Published studies have used different methods of assessing psoriasis severity, and each method has various benefits and drawbacks. Affected body surface area (BSA) is useful for assessing disease severity and outcomes in clinical settings but does not describe symptoms or disease location. The Investigator’s Global Assessment (IGA) modified 2011 scale, used in clinical trials, takes skin symptoms (eg, redness, thickening, and scaling) into account but has not been evaluated in real-world psoriasis-related quality-of-life assessments.1

Strober and colleagues used real-world data to examine associations between psoriasis severity and symptom severity, quality of life, and work productivity. They performed separate data analyses for psoriasis severity as measured by BSA and by IGA.1


The cross-sectional study used data from patients enrolled in the Corrona Psoriasis Registry, an observational cohort of US adults who received a systemic psoriasis therapy within the year before enrollment. The data analysis included patients enrolled from April 2015 through May 31, 2016, from 70 dermatology practices.1

Data collected for this study included demographics, disease duration, systemic psoriasis treatments currently or previously used, comorbidities, disease severity, and patient-reported outcomes (PROs). Disease severity was determined by affected BSA and/or the IGA modified 2011 scale. In this study, levels of severity according to percentage of affected BSA were mild (0%-5%), moderate (>5%-10%), severe (>10%-15%), and very severe (>15%). Levels of severity according to IGA score, looking at redness, skin induration, and scaling, were clear/almost clear (0-1), mild (2), moderate (3), and severe (4).1

The PROs examined were pain, itching, and fatigue levels as assessed by visual analog scale; health-related quality of life, assessed by the Dermatology Life Quality Index (DLQI) and the EuroQol Visual Analogue Scale (EQ-VAS); and work productivity, assessed by the Work Productivity and Activity Impairment (WPAI) questionnaire. The investigators used analysis of variance and χ2 tests to compare PROs across psoriasis severity levels and used multivariable linear regression to determine associations between PROs and psoriasis severity levels.1


The analysis included 1529 patients (mean age, 50.6 years; 47% women). Descriptive analyses indicated that pain, itching, and fatigue levels, DLQI scores, EQ-VAS status, and work productivity all worsened as disease severity increased.1

Multivariable regression revealed associations consistent with the descriptive analyses. Worse pain, itching, and fatigue were associated with higher BSA and IGA severity levels (P <.001 at all levels), as were worse DLQI and EQ-VAS scores (P <.05 at all levels).1

In the analysis of WPAI domains according to BSA-defined severity, the categories of moderate, severe, and very severe disease were associated with poorer outcomes for “impairment while working” and “daily activities impaired”; very severe disease was associated with increased “work hours missed”; and moderate and very severe disease were associated with increased “work hours affected” compared with mild disease (all P <.05). Analysis according to IGA models yielded similar results: Mild, moderate, and severe categories were associated with poorer outcomes in the WPAI field for “daily activities impaired” compared with the clear/almost clear category, and moderate and severe categories were associated with worse outcomes for “work hours missed,” “impairment while working,” and “work hours affected” compared with the mild category (all P <.05).1


To the authors’ knowledge, this is the first study to investigate the association between IGA-defined psoriasis severity and PROs using real-world data. The results were consistent for BSA-defined and IGA-defined severity levels.1

The authors noted that the BSA and IGA categories used in this study differed from those in previously published studies. They suggested that additional research is necessary to examine how differences in BSA severity definitions could affect the results of observational studies and clinical trials.1

Because this was a cross-sectional study, causal inferences about disease severity and outcomes could not be made, and results of the study did not show how changes in disease severity over time might affect outcomes. Another limitation was that patients enrolled in the registry might not represent the general population of patients with psoriasis.1


More severe psoriasis (measured by either BSA or IGA) was associated with poorer PROs for patients enrolled in the Corrona Psoriasis Registry. The authors recommended further studies to explore relationships between various health outcomes in patients with psoriasis and to determine whether improvements in psoriasis severity over time are related to improvements in outcomes.1


1. Strober B, Greenberg JD, Karki C, et al. Impact of psoriasis severity on patient-reported clinical symptoms, health-related quality of life and work productivity among US patients: real-world data from the Corrona Psoriasis Registry. BMJ Open. 2019;9(4):e027535. doi: 10.1136/bmjopen-2018-027535.