Arterial and venous thrombosis in patients with monoclonal gammopathy of undetermined significance: incidence and risk factors in a cohort of 1491 patients

Summary Monoclonal gammopathy of undetermined significance (MGUS) has been associated with an increased risk of thrombosis. We carried out a retrospective multicentre cohort study on 1491 patients with MGUS. In 49 patients (3·3%) MGUS was diagnosed after a thrombotic event. Follow-up details for a period of at least 12 months after diagnosis of MGUS were obtained in 1238 patients who had no recent history of thrombosis ( 16 g/l at diagnosis (HR 3·08, 95%CI 1·01–9·36). No thrombosis was recorded in patients who developed multiple myeloma (n = 50) or other neoplastic diseases (n = 21). The incidence of arterial or venous thrombosis in patients with MGUS did not increase relative to that reported in the general population for similarly aged members. Finally, the risk of venous thrombosis did increase when the M-protein concentration exceeded >16 g/l.