The relationship between inflammation and venous thrombosis - A systematic review of clinical studies

During the past decade, the role of inflammation in the pathophysiology of arterial thrombosis has been elucidated. However, comparatively little is known about the relationship between inflammation and venous thrombosis. The aim of this study was to perform a systematic review of clinical studies that have examined the association between inflammation and venous thrombosis, specifically: (1) the value of inflammatory markers in predicting the future development of venous thrombosis; (2) test characteristics of markers of inflammation in the diagnosis of acute venous thrombosis; and (3) effect of venous thrombosis on blood levels of inflammatory markers. Using keywords venous thrombosis, venous thromboembolism, inflammation, acute phase markers, C-reactive protein (CRP), interleukin (IL)-6, IL-8, and monocyte chemotactic protein (MCP)-I, PubMed and Medline computerized databases were searched for English language articles published after 1980. Search results were restricted to clinical studies in humans that used study designs that were appropriate to address the above objectives. Results show that plasma CRP levels do not appear to predict risk of future venous thrombosis (two studies; N=41,308). Four studies (N=562) have examined the utility of plasma CRP in the diagnosis of venous thrombosis; pooled positive and negative predictive values were 53% (95% 0:47%,59%) and 85% (95% Cl: 81%,89%), respectively. A two- to six-fold increase in the risk of deep vein thrombosis (DVT) is associated with elevations in plasma levels of CRP, IL-6, IL-8, MCP- I or TNF-alpha (three studies). We can conclude that the nature of the relationship between inflammation and clinical venous thrombosis is not yet established. CRP does not appear to be useful in predicting future venous thrombosis or in the diagnosis of acute venous thrombosis. While several markers of inflammation are elevated in acute venous thrombosis, further research is needed to determine the precise relationship between these markers and venous thrombosis. The identification and elucidation of inflammatory markers relevant to venous thrombosis could provide targets for future therapy.