Prevalence of Psoriasis and Rosacea Comorbidities in the Outpatient Setting

To the Editor: Psoriasis and rosacea are common, chronic inflammatory skin conditions that may affect a patient’s overall health. Whereas many psoriasis comorbidities have been identified, there are limited data for rosacea patients. Successful management of comorbidities may impact the health status and treatment outcomes among such patients. The purpose of this study was to assess the frequencies of comorbid conditions in patients with rosacea and to compare these frequencies to those of comorbidities among patients with or patients without psoriasis. This study was conducted using the MarketScan Medicaid data set, which contains individual-level health care claims, and hospital discharge information from large organizations and public health insurance programs. Overall, the database covers almost 10 million patients in the United States and captures the full continuum of care in all health care settings. Patients who were 18 years of age or older and had made at least one outpatient visit during the time period of 2003–2007 were included. Demographic information was described. Comorbidities were identified by ICD-9 codes in the outpatient data file (Table 1). The frequencies and 95% confidence intervals of the top 10 comorbidities were calculated through direct age standardization based on the number of patients associated with the following patient populations: (1) all patients without psoriasis; (2) psoriasis patients; and (3) rosacea patients. Statistical analyses were performed using Stata 12 software (StataCorp LP, College Station, TX). The total number of patients without psoriasis was 4,544,189, the total number of patients with psoriasis was 24,247, and the total number of patients with rosacea was 13,026. For all three populations, patients tended to be white and female (Table 2). The most common age category for all patients without psoriasis was 18 to 30 years; in contrast, the most common age group for patients with psoriasis or rosacea was 51 years and older. The top 10 comorbidity diagnoses based on patient counts were similar across all three patient groups. However, the frequencies of comorbidities across the three groups differed, with rosacea and psoriasis patients having the higher proportions of patients affected compared to patients without psoriasis (Table 3). Acute bronchitis/ bronchiolitis was a top 10 comorbidity unique to psoriasis patients. Unlike patients without psoriasis, patients with psoriasis or rosacea frequently experienced limb pain. These findings indicate that psoriasis and rosacea adult patients share multiple comorbidities in common with the general patient population, but these two groups have higher comorbidity burdens. Psoriasis is a systemic autoimmune disease that affects about 7.5 million people in the United States alone. It is driven by aberrant T cell– mediated activity that tips the balance of cytokine activity in the body to drive inflammation. As a result, psoriasis has many associated comorbidities, such as hypertension, type 2 diabetes, metabolic syndrome, hyperlipidemia, and obesity. Our results validate these findings as diabetes, hypertension, and hyperlipidemia were common comorbidities for psoriasis patients. Although rosacea affects an estimated 14 million people in the United States, much remains unknown about the disease process, with theories including vascular abnormalities, dermal matrix degeneration, and environmental factors. Hypertension and hyperlipidemia were among the top 10 ranked comorbidities in rosacea patients, consistent with findings from a previous study. Similar to findings from Gupta and colleagues, depressive disorder was also a common rosacea comorbidity. These findings reinforce the known inflammatory-related comorbidities associated with psoriasis and highlight the need for further study of rosacea comorbidities.