Lupus (2017) 0, 1–5 journals.sagepub.com/home/lup CONCISE REPORT Cutaneous lupus erythematosus and the risk of deep venous thrombosis and pulmonary embolism: A Danish nationwide cohort study O Ahlehoff 1 , JJ Wu 2 , J Raunsø 3 , SL Kristensen 3 , U Khalid 3 , K Kofoed 4 and G Gislason 3 1 Department of Cardiology, Odense University Hospital, Odense, Denmark; 2 Department of Dermatology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, CA, USA; 3 Department of Cardiology, Copenhagen University Hospital Herlev and Gentofte, Herlev, Denmark; and 4 Department of Dermatology, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark Background: Venous thromboembolism (VTE) is a major public health concern. Lupus erythe- matosus (LE) is a chronic autoimmune disease ranging from localized cutaneous disease (CLE) to systemic involvement (SLE). Patients with SLE have an increased risk of venous thromboembolism (VTE), but little is known about the CLE-related risk of VTE. Methods: To evaluate the risk of VTE in patients with SLE and CLE as compared to the general population, a retrospective cohort study was conducted. Incidence rates and hazard ratios (HRs) with 95% confidence intervals (CIs) from multivariable Cox regression models were used to evaluate and compare the risk of VTE. Registries of hospitalizations, outpatient visits, and prescription drug use were studied to determine the risk of VTE in patients with CLE and SLE and the general population between 1997 and 2011. Results: A total of 3234 patients with CLE and 3627 patients with SLE were identified and compared to 5,590,070 individuals in the reference population. The incidence rates per 1000 year of VTE were higher in patients with LE, i.e. 1.20, 3.06, and 5.24 for the reference population, CLE, and SLE, respectively. In adjusted models, both CLE (HR 1.39; 95% CI 1.10–1.78) and SLE (HR 3.32; 95% CI 2.73– 4.03) were associated with a statistically significant increased risk of VTE, compared to the reference population. Conclusion: In this nationwide study, both CLE and SLE were signifi- cant risk factors for VTE. The results add to our understanding of comorbidities in patients with LE, and call for further studies and increased awareness of thromboembolic complica- tions in patients with CLE. Lupus (2017) 0, 1–5. Key words: Lupus erythematosus; venous thromboembolism; epidemiology Introduction Venous thromboembolism (VTE), i.e. deep vein thrombosis (DVT) and pulmonary embolism (PE), is a public health concern and it has been estimated that up to 600,000 people in the United States suffer a VTE each year. 1 Research has indi- cated that several immune-inflammatory diseases might be associated with an increased risk of VTE. 2 Lupus erythematosus (LE) is a chronic auto- immune disease that ranges from localized cutane- ous disease (CLE) to systemic involvement (SLE). 1 Indeed, an increased risk of VTE associated with SLE has been reported previously, but little is known about the risk of VTE in patients with CLE. 2,3 We therefore used nationwide registries of hospitalization, outpatient visits, and drug dispen- sing from pharmacies to determine the risk of VTE in patients with CLE as compared to SLE and the general population. Methods Data sources and study population The study was approved by the Danish Data Protection Agency, and registry studies are exempted from ethics committee review in Denmark. The study comprised all Danish individ- uals aged 18 years from 1997 to 2011. The personal Correspondence to: O Ahlehoff, Department of Cardiology, Odense University Hospital, Sdr Boulevard, Odense, DK-5000 Denmark. Email: ole.ahlehoff@regionh.dk Received 19 April 2017; accepted 25 May 2017 ! The Author(s), 2017. Reprints and permissions: http://www.sagepub.co.uk/journalsPermissions.nav 10.1177/0961203317716306