Prevalence and comorbidities in adults with psoriasis compared to atopic eczema

Background Most data suggesting an association between psoriasis and cardiovascular disease (CVD) have come from specialized populations at either low or high risk of CVD. Atopic dermatitis (AD) has been associated with a number of modifiable risk factors, particularly obesity. There has been a recent controversy on the suggestion that associations with comorbidities in psoriasis may be due to overreporting or biased by disease severity and therefore not necessarily representative of the general psoriasis population. Objectives To evaluate the prevalence of AD and psoriasis and to compare the prevalence rates of comorbidities based on a large sample of health insurance data. Methods Data were collected from a database of non-selected individuals from a German statutory health insurance organization that covers all geographic regions. Individuals identified by International Classification of Diseases (ICD)-10 codes applied to all outpatient and inpatient visits in the year 2009. Comorbidities were evaluated by ICD-10 diagnoses. Results The database consisted of 1 642 852 members of a German statutory health insurance. Of 1 349 671 data sets analyzed, 37 456 patients >= 18 years were diagnosed with psoriasis (prevalence 2.78%), and 48 140 patients >= 18 years of age were diagnosed with AD, equivalent to a prevalence of 3.67%. Patients with psoriasis showed increased rates of comorbidities in all age groups. Comorbidities related to the metabolic syndrome including arterial hypertension [prevalence ratio (PR), 1.94; 95% confidence interval (CI), 1.90-1.98], hyperlipidaemia (PR, 1.77; 95% CI, 1.73-1.81), obesity (PR, 1.74; 95% CI, 1.69-1.79) and diabetes mellitus (PR, 1.88; 95% CI, 1.83-1.94) were significantly more common among patients with psoriasis compared to AD. Conclusions Diseases forming part of the metabolic syndrome showed significant lower prevalence rates in patients with AD than in patients with psoriasis. Within the limitations of secondary healthcare data, our study disproves the suggestion that associations with comorbidities in psoriasis may be biased by a higher degree of severity or overreporting.