Epidemiology and natural history of venous thromboembolism

Abstract

I N 1975, WE reviewed the natural history and epidemiology of pulmonary embolism (PE). Since then, a great deal has been learned about the pathophysiology, diagnosis, and treatment of venous thromboembolism (VTE). However, less is known about the natural history and epidemiology of this condition because the diagnosis is often based on clinical data that are fraught with uncertainty. Thus, it is still difficult to ascertain the true incidence and case fatality rate of acute VTE, even though PE is listed as one of the monitored causes of death by the National Center for Health Statistics. a Problems in determining the true incidence and lethality of VTE are compounded by the considerable degree of inaccuracy inherent in death certificate assignment of mortality in patients with suspected VTE. 2 Indeed, the clinical diagnosis of PE remains notoriously inaccurate. 3 Even ventilation/perfusion pulmonary scintigraphy is often incorrect in ascertaining the diagnosis of VTE, as was recently reconfirmed by the Prospective Investigation of Pulmonary Embolism Diagnosis study. 4 Therefore, inaccuracies inherent in the clinical, death certificate, and even autopsy diagnosis of VTE continue to confound attempts to estimate incidence/ prevalence and case fatality rates of this common condition. 5 Further complicating this analysis is the fact that, for many patients, VTE is the final event in a prolonged and inevitably fatal illness. 5 Fatal VTE may even be welcomed in such a setting. What the clinician and the clinical scientist would really like to ascertain is the number of patients who have VTE as an acute primary or an important secondary event, ie, how many patients actually require diagnosis and therapy for VTE. Estimates of the latter number of patients will remain uncertain until an accurate, simple clinical test for the diagnosis of VTE becomes available, thereby making pulmonary angiography unnecessary.