317 Comparative risk of venous thromboembolism (VTE) among patients with atopic dermatitis (AD) or other immune-mediated diseases: a cohort study using United States claims data
Authors: Merola Joseph F , Danwada Raghava , Ertmer Brennan , Liang Huifang , Ofori Sarah , Krueger Whitney 
Published: January 2023

Abstract
Patients with rheumatoid arthritis (RA) or inflammatory bowel disease (IBD) are at increased risk for thrombotic events, but less is known about the underlying risk of VTE with immune-mediated skin conditions. The objective of our study was to describe the incidence of VTE among patients diagnosed with AD and compare VTE incidence among patients with other immune-mediated inflammatory diseases, as well as among individuals without such conditions. This retrospective, observational, comparative cohort study used a large national administrative claims database Optum® (Clinformatics® Data Mart). Adults (aged ≥18 years) diagnosed with AD, RA, IBD (Crohn’s disease [CD] or ulcerative colitis [UC]) or other immune-mediated diseases during 2010–2019 were included. Disease cohorts were not mutually exclusive. A non-diseased control population with no such diagnoses was matched 1 : 1 to patients in the AD cohort by age, sex and calendar time of cohort entry. All patients had to have at least 12 months of enrolment (baseline) before a confirmed diagnosis (or matched cohort entry date for controls) and at least 1 day of follow-up data following diagnosis. All patients received normal clinical care and were followed until the earliest VTE event, end of health plan enrolment, death or end of data availability (30 June 2021). The primary outcome was the incidence of VTE (deep vein thrombosis [DVT] or pulmonary embolism [PE]) defined as an inpatient hospitalization with a VTE diagnosis and length of stay ≥1 day or an outpatient VTE diagnosis followed by initiation of an anticoagulant within 7 days. Incidence per 100 person-years (PY) and 95% CI were calculated. Crude and adjusted hazard ratios (HRs) were determined using Cox proportional hazards regression models and adjusted for demographic and comorbid disease factors. The secondary outcome was the incidence of VTE limited to inpatient events. A total of 1,098,633 adults with AD were included in the analysis; the mean (SD) age was 54.1 (18.5) years, 65.3% were female and 1.1% had a history of VTE. A total of 15,456 VTE events (primary outcome) were reported among patients with AD during 2,113,668.9 PY for a crude incidence (95%CI) of 0.73 (0.72, 0.74) cases/100 PY. The incidence of VTE was 1.33 (1.30, 1.36) cases/100 PY among patients with RA or IBD (n = 578,021) and 0.59 (0.58, 0.60) cases/100 PY among AD-matched controls. The adjusted risk for VTE was higher among patients with RA or IBD compared with patients with AD with an adjusted HR (95% CI) of 1.46 (1.43, 1.49). Patients with AD had a slightly higher risk for VTE compared with AD-matched controls with an adjusted HR of 1.09 (1.06, 1.12). Similar results were observed when DVT and PE were assessed separately. Patients with CD or UC had the highest risk for VTE relative to patients with AD with an adjusted HR of 1.61 (1.54, 1.69) and 1.57 (1.5, 1.63), respectively. Patients with RA also had a higher risk for VTE relative to patients with AD with an adjusted HR of 1.42 (1.38–1.46). Similar results were also observed when the assessment of the incidence and risk of VTE was limited to inpatient events. Patients with RA or IBD had a higher risk of VTE compared with patients with AD. The risk of VTE was slightly higher among patients with AD compared with AD-matched controls. Because VTE risk is increased in RA and IBD during periods of active disease, observed rates may depend on the proportion of patients with uncontrolled disease. Characterization of baseline VTE risk among patients with AD may better inform treatment benefit–risk assessments and shared decision-making.