Infections increase risk of arterial and venous thromboses in Danish patients with systemic lupus erythematosus: 5102 patient-years of followup.

Abstract

Infections and thromboses are known complications of systemic lupus erythematosus (SLE). We investigated if infectious episodes in patients with SLE were followed by an increased risk of thrombotic events. A cohort of 571 patients with prevalent or incident SLE was followed for a mean of 8.9 ± 7.6 years. All episodes of hospitalized infections or episodes of cutaneous herpes zoster as well as arterial and venous thrombotic events were identified by retrospective chart review and prospective updating of a clinical database. For time-dependent analyses adjusted for age, sex, and ever-presence of antiphospholipid antibodies, thrombotic events were classified as occurring during the time at risk of 1 year after an infection or during the remaining control observation time. Of 271 infections identified, 104 were respiratory, 41 cutaneous herpes zoster, and 126 others. Of 159 thromboses identified, 98 were arterial. Incidence for arterial and venous thromboses within 1 year after infection was 2.18% and 2.56%, respectively, compared to patients who never had an infection (0.58 and 0.67). The adjusted 1-year risk of arterial and venous thrombosis after any infection was increased [relative rate (RR) 2.5, 95% CI 1.4-4.6, and RR 2.8, 95% CI 1.3-5.9, respectively]. Venous thromboses were in particular more prevalent after respiratory infections (RR 5.4, 95% CI 2.3-13). The temporal associations observed in this study indicate that infections could be risk factors for arterial or venous thromboses in patients with SLE, although causality was not addressed by this study.