Long-term adverse effects associated with isolated below-knee deep-vein thrombosis: a 10-year follow-up study

Aim To assess the effect of the presence and locality of symptomatic lower-limb deep vein thrombosis (DVT) on mortality and morbidity following contrast venography (CV), the reference standard for diagnosing below-knee DVT, with a view to determining the prevalence of recurrent episodes of DVT and post-thrombotic syndrome (PTS). Materials and methods Patients with clinical DVT undergoing investigation using CV were prospectively recorded. By retrospective case note examination and mortality data evaluation, 347 patients with DVT were matched with negative controls for mortality follow-up. Long-term complications were recorded. Results Fifty-one (14.7%) of the DVT patients were diagnosed with PTS and 43 (12.4%) with possible PTS in the 10 years following presentation. The relative risk for developing definite PTS was 0.544 for below- versus above-knee DVT; 9.9% with below-knee DVT had PTS, and 9% had probable PTS. Recurrent DVT occurred in 23.3% of patients with proximal DVT as opposed to 12.6% of patients with isolated below-knee DVT. Conclusions Morbidity is greater in patients with proximal DVT; however, a significant, albeit smaller, proportion of patients with isolated below-knee DVT develop recurrent DVT and PTS. Below-knee DVT carries sufficient morbidity and mortality to warrant vigilance in diagnosis and management of this condition.