CPTA linked to pulmonary embolism overdiagnosis
MedWire News: Cases of pulmonary embolism (PE) have risen dramatically, but mortality has only increased slightly, since the introduction of computed tomographic pulmonary angiography (CTPA) in 1998, US researchers report
They say that this "increased incidence of PE reflects an epidemic of diagnostic testing that has created overdiagnosis" where many of the cases are "clinically unimportant" and "would not have been fatal even if left undiagnosed and untreated."
Renda Soylemez Wiener (Boston University School of Medicine, Massachusetts) and colleagues assessed the impact of highly sensitive CTPA on PE incidence, mortality, and treatment complications using data from the US Nationwide Inpatient Sample and Multiple Cause-of-Death databases.
They found that PE incidence did not change significantly during the period before CTPA introduction, increasing slightly from 58.8 cases per 100,000 US adults in 1993 to 62.3 cases per 100,000 US adults in 1998. In contrast, the number of cases nearly doubled after the introduction of CTPA, going from 62.3 cases per 100,000 in 1998 to 112.3 cases per 100,000 in 2006.
PE mortality decreased significantly during both periods, but the decrease was more pronounced before CTPA, at 8% (from 13.4 to 12.3 deaths per 100,000 US adults), than afterwards, when mortality fell by 3% (from 12.3 to 11.9 deaths per 100,000).
In addition, the researchers observed an 8% decrease in the case-fatality rate in the period before CPTA (from 13.2% to 12.1%), compared with a 36% decrease after CPTA (from 12.1% to 7.8%). The greater decrease post-CTPA again points to overdiagnosis "because the denominator [people diagnosed] has been inflated with clinically insignificant cases that are only identifiable by highly sensitive tests," they say.
Wiener and co-authors stress in the Archives of Internal Medicine that "overdiagnosis matters because treatment of PE can cause real harm." Indeed, in the present study, the rate of complications (in-hospital gastrointestinal tract or intracranial hemorrhage, or secondary thrombocytopenia) was stable before CTPA, but increased by a significant 71%, from 3.1 to 5.3 cases per 100,000, after its introduction.
In an accompanying comment Victor Tapson (Duke University Medical Center, Durham, North Carolina, USA) said: "There is good evidence that overdiagnosis is a real phenomenon, but it is very likely that a subset of patients with 'incidental' PE benefits from therapy."
He added that "autopsy studies, with their inherent limitations, suggest that PE is clearly also underdiagnosed and that most patients who die from acute PE are not only not diagnosed until death but are not even suspected."
Therefore, "prevention remains crucial."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Laura Dean