Natural history of pulmonary embolism

Abstract

Listen

Translate article

A FULL UNDERSTANDING of the natural history of pulmonary embolism is elusive at the present time because many basic facts are either uncertain or unknown. For example, the acute mortality of pulmonary embolism is not known because the numerator (number of pulmonary embolism deaths per year) is uncertain, and the denominator (the total incidence of pulmonary embolism) is unknown. Let us first consider the numerator; the total number of PE deaths per year. Why should this number be uncertain? The usual technique of estimating the incidence of fatal diseases is to study the causes of death listed on death certificates. This technique is not appropriate for assessing the incidence of pulmonary embolism for several reasons. First, the clinical diagnosis of pulmonary embolism is notoriously inaccurate. 1 Second, pulmonary embolism rarely occurs de novo in previously healthy patients. Rather, it usually occurs as a complication of other potentially fatal diseases-particularly heart disease. This fact makes it very difficult to classify the primary cause of death in patients in whom pulmonary embolism occurs as a fatal complication of other diseases. For example, in England and Wales in 1967, pulmonary embolism was listed as the primary cause of death on 4,981 death certificates. However, when a sample of cases was analyzed with regard to multiple causes of death, the total number of pulmonary embolism deaths in England and Wales was estimated to be 21,000) If one extrapolates these numbers to the United States population, it would lead to an estimate of 88,200 pulmonary embolism deaths per year in the United States. The most frequently cited estimate of the number of pulmonary embolism deaths per year in the United States is 47,000. This was estimated by Coon and Willis in 1959. 3 It was based on the incidence of pulmonary embolism at postmortem examinations performed at the University of