Overdiagnosis of pulmonary embolism: definition, causes and implications

Overuse of computed tomography pulmonary angiography to diagnose pulmonary embolism in people who have only a low pre-test probability of pulmonary embolism has received significant attention in the past. The issue of overdiagnosis of pulmonary embolism, a potential consequence of overtesting, has been less explored. The term “overdiagnosis”, used in a narrow sense, describes a correct (true positive) diagnosis in a person but without any associated harm. The aim of this review is to summarise literature on the topic of overdiagnosis of pulmonary embolism and translate this epidemiological concept into the clinical practice of respiratory professionals. The review concludes that the location of pulmonary embolism at a subsegmental level, rather than whether a diagnosis was made incidentally or following an investigation for suspected pulmonary embolism, is the best predictor for situations in which anticoagulation may not be necessary. In the absence of strong evidence of the optimal management of subsegmental pulmonary embolism, treatment decisions should be made case by case, taking into account the patient's situation and preference. KEY POINTS: Since the introduction of computed tomography pulmonary angiography in 1998, there has been a steep increase in the diagnosis of pulmonary embolism (PE). An increased incidence of PE diagnoses, but an almost stable mortality from PE in the population, together with a decreased case fatality, point towards overdiagnosis (in the absence of more effective treatment). Whether PE is diagnosed as an incidental finding or following an investigation for suspected PE does not appear to influence the need for anticoagulation therapy. An isolated subsegmental PE may not require anticoagulation therapy, and treatment decisions should be made case by case, taking into account the patient's situation and preference. A suggested definition of overdiagnosis of PE: a diagnosis of PE that, if left untreated, would not lead to more harm than if it were treated with anticoagulation therapy, independent of symptoms. EDUCATIONAL AIMS: To understand the term “overdiagnosis” based on its narrow definition and be able to apply it to PE. To outline the diagnostic approach to PE. To summarise what is known about the treatment of incidentally detected PE. To summarise what is known about the treatment of subsegmental PE. To understand in which situations anticoagulation therapy for PE may not be beneficial.