Prevalence and Comorbidity Burden Among Adults with Psoriasis in the United States

Abstract

Background: Information is sparse concerning the prevalence and associated comorbidities of psoriasis in the United States (U.S.) civilian noninstitutionalized population. The objectives of this study were to determine the national proportion of patients who self-report psoriasis diagnosed by a physician and to explore the comorbidity burden of these patients. Methods: This study used ten years of retrospective, cross-sectional data from the Medical Expenditure Panel Survey (MEPS) (2006–2015). The study population included adults (age≥18 years) who did not die during the calendar year the survey was completed and had an ICD-9-CM code of 696.xx (psoriasis and similar disorders) based on individual self-reports of illness. Subtypes were categorized as those with and without joint involvement to assess the number of persons who had skin-only psoriasis, and those who may have psoriatic arthritis via reporting joint pain in the last 12 months. Bivariate, multivariate, and propensity score matched methods using logistic regression were performed, accounting for multiple comparisons, to appraise the association of diseases between the psoriasis case and control groups. Results: The self-reported prevalence of previously diagnosed psoriasis was found to be 0.80% (n=719, 95% CI=0.73-0.88%) of the population on average over the ten year study period. Psoriasis patients with skin-only manifestations accounted for 0.30% (n=269, 95% CI=0.25-0.34%) of the population versus those who may have psoriatic arthritis 0.51% (n = 450, 95% CI=0.44-0.57%). Analyses showed psoriasis patients were more than twice as likely to report other autoimmune diseases than those without psoriasis. The bivariate [Odds Ratio (OR)=2.72], multivariate [Adjusted Odds Ratio (AOR)=2.50], and propensity score method (AOR=2.62) produced approximately similar magnitudes of association at the P<0.00125 level. Similar findings were seen with rheumatoid arthritis, mood disorders, gastroesophageal reflux disease (GERD), and COPD. Conclusions: These study findings are some of first analyses of prevalence and comorbidity patterns of psoriasis based on a nationally representative survey of the U.S. civilian noninstitutionalized population. The prevalence of psoriasis is low, but there are several associated comorbid conditions and clusters of diseases such as other autoimmune diseases like rheumatoid arthritis that may benefit from future analyses to appropriately plan for treatment, and insurance needs. These associations may help assess healthcare expenditures, healthcare use, and provide context to disease etiology.