Background
Atopic dermatitis (AD) is associated with substantial impairment in quality of life, including sleep disturbances, anxiety, and depression, which may increase the risk of cardiovascular disease (CVD). However, the association between CVD and AD is not well established.

Objectives
To evaluate incidence rates (IRs) of venous thromboembolism (VTE), deep vein thrombosis (DVT), and pulmonary embolism (PE) in patients with and without AD in a population-based cohort study in Denmark, and to assess IRs of malignancies, major adverse cardiovascular events (MACE), VTE, and the distribution of Atherosclerotic Cardiovascular Disease (ASCVD) risk factors in patients with AD and rheumatoid arthritis (RA) in a nested cohort analysis.

Methods
Data from all individuals aged ≥12 years (≥18 years in the nested cohort analysis) between January 1, 2000, and December 31, 2018, were extracted from the Danish National Patient Registry. Patients with ≥1 AD diagnosis during the study period were matched on sex and age with 10 individuals from the general population. The nested cohort analysis included patients diagnosed with RA as an additional comparison population. In the overall cohort, IRs of VTE, DVT, and PE were assessed; the nested cohort analysis evaluated the distribution of ASCVD risk factors and incidence of malignancies, MACE, and VTE in patients with and without ASCVD risk factors (age ≥65 years, and history of smoking, coronary artery disease, stroke, DVT, PE, and malignancy). The follow-up period was from the first diagnosis during the study period until the occurrence of death or an endpoint, the first instance of migration, or December 31, 2018. IRs are shown per 100 patient-years (PY) of exposure with 95% confidence intervals.

Results
The population-based cohort comprised 190,751 patients, including 17,341 patients with AD and 173,410 age- and sex-matched controls. The IR/100 PY of VTE was similar between the AD cohort (0.14 [95% CI, 0.12-0.16]) and the general population (0.11 [0.11-0.12]). The IR/100 PY for VTE was higher in patients with AD aged ≥65 years (0.71 [0.56-0.90]) than the age-matched general population (0.50 [0.46-0.54]) and lower in the younger AD cohorts (12 to <18 years, 0.02 [0.00-0.08]; 18 to <65 years, 0.12 [0.09-0.13]). The IRs/100 PY of DVT and PE were comparable between the AD cohort (DVT, 0.08 [0.06-0.09]; PE, 0.06 [0.05-0.08]) and the general population (DVT, 0.06 [0.06-0.07]; PE, 0.05 [0.05-0.05]).. The nested cohort analysis comprised 195,807 patients, including 13,432 with AD, 48,055 with RA, and 134,320 age- and sex-matched controls. Distribution of risk factors for malignancies (excluding nonmelanoma skin cancer [NMSC]), MACE, and VTE was comparable in the AD cohort and general population, but higher in patients with RA. The IR/100 PY for malignancies (excluding NMSC) was higher in patients with AD with a history of malignancy (11.41 [9.83-13.25]) than those without (0.44 [0.40-0.48]), and in those aged ≥65 years (3.09 [2.75-3.48]) versus <65 years (0.36 [0.33-0.40]). Similarly, the IR/100 PY for MACE was higher in patients with AD aged ≥65 years (2.30 [2.01-2.63]) versus <65 years (0.15 [0.13-0.17]), and patients with a history of ASCVD (5.02 [4.37-5.76]) versus without (0.15 [0.13-0.18]). Patients with AD with a history of VTE (including DVT/PE) and inherited thrombophilia had a greater risk of VTE than patients without these risk factors.

Conclusions
In these 2 large cohort studies of adults and adolescents with AD, IRs of VTE, DVT, and PE were comparable with the general Danish population. The risk of VTE, malignancy, and MACE was higher in patients with AD with a history of risk factors for ASCVD. This underscores the need for appropriate monitoring and reporting of cardiovascular events in patients with AD, and active management of risk factors with early and effective therapeutic intervention.