THE RELATIONSHIP BETWEEN DISEASE SEVERITY AND QUALITY OF LIFE IN PATIENTS WITH MODERATE TO SEVERE PSORIASIS
Author(s)
Geale K1, Henriksson M2, Schmitt-Egenolf M1
1Umeå University, Umeå, Sweden, 2Linköping University, Linköping, Sweden
Presentation Documents
OBJECTIVES: Psoriasis is prevalent in approximately 3% of the population, and often results in significant quality of life losses. The aim of this study was to investigate the relationship between disease severity and quality of life (QOL) measured by the psoriasis area severity index (PASI) and EQ-5D, respectively. METHODS: Longitudinal data from a population-based registry in Sweden (PsoReg) were analysed. PsoReg includes patients with moderate to severe psoriasis receiving systemic treatment from a specialist with data available from 2006 to 2014. The analysis was conducted using all complete observations for adult patients at each healthcare contact date. A fixed effects (FE) model was estimated, where time-invariant patient-specific effects were modelled. Time-invariance refers to variables that do not change over time, such as sex or personality. PASI, PASI squared, age, body mass index, smoking status, and presence of psoriatic arthritis were included in the regression as independent variables. PASI squared accounts for a nonlinear relationship between PASI and EQ-5D. The model was tested for the appropriateness of random effects and existence of group-wise homoscedasticity, both of which were rejected at an alpha level of 0.01. Therefore the final model used FE and robust standard errors. RESULTS: The estimation utilised 15,099 observations in 3,838 groups, resulting in an average of 3.9 observations per patient. The results indicate that each unit increase in PASI is correlated with a reduction in EQ-5D, but at a decreasing rate: the estimates of PASI and PASI squared were -0.0178 (p<0.001) and 0.0002 (p<0.001) respectively. This implies that an increase in PASI of 10 (20) units results in a decrease in EQ-5D of 0.1571 (0.2717) holding other variables constant at their respective means. The (adjusted) R was (0.5279) 0.6481. CONCLUSIONS: QOL in psoriasis patients is decreasing as disease severity increases, but at a decreasing rate
Conference/Value in Health Info
2015-11, ISPOR Europe 2015, Milan, Italy
Value in Health, Vol. 18, No. 7 (November 2015)
Code
PSY95
Topic
Patient-Centered Research
Topic Subcategory
Patient-reported Outcomes & Quality of Life Outcomes
Disease
Systemic Disorders/Conditions