Prevalence of deep vein thrombosis and pulmonary embolism in patients with superficial vein thrombosis: a systematic review and meta-analysis

Background: Some studies have suggested that patients with superficial vein thrombosis (SVT) have a non-negligible risk of concomitant deep vein thrombosis (DVT) or pulmonary embolism (PE) at the time of SVT diagnosis. Unfortunately, the available data on this association are widely variable. Objectives: To perform a systematic review and meta-analysis of the literature in order to evaluate the prevalence of concomitant DVT/PE in patients with SVT of the lower limbs. Methods: Studies reporting on the presence of DVT/PE in SVT patients were systematically searched for in the PubMed, Web of Science, Scopus and EMBASE databases. The weighted mean prevalence (WMP) of DVT and PE was calculated by use of the random effect model. Results: Twenty-one studies (4358 patients) evaluated the prevalence of DVT and 11 studies (2484 patients) evaluated the prevalence of PE in patients with SVT. The WMP of DVT at SVT diagnosis was 18.1% (95% CI: 13.9%, 23.3%) and the WMP of PE was 6.9% (95% CI: 3.9%, 11.8%). Heterogeneity among the studies was substantial. Selection of studies including outpatients only gave similar results (WMP of DVT, 18.2%, 95% CI 12.2-26.3%; and WMP of PE, 8.2%, 95% CI 3.3-18.9%). Younger age, female gender, recent trauma and pregnancy were inversely associated with the presence of DVT/PE in SVT patients. Conclusions: The results of our large meta-analysis suggest that the prevalence of DVT and PE in patients presenting with SVT is not negligible. Screening for a major thromboembolic event may be worthwhile in some SVT patients, in order to allow adequate anticoagulant treatment to be planned. Other high-quality studies are warranted to confirm our findings.