Prevalence of Pulmonary Embolism Among Patients with Acute Exacerbations of Chronic Obstructive Pulmonary: Data from Nationwide Inpatient Sample

Background

Patients suffering from acute exacerbation of chronic obstructive pulmonary disease (AECOPD) are thought to be at a higher risk of developing venous thromboembolism due to various reasons such as smoking, immobilization and a transient procoagulant state. However, clinical diagnosis of acute pulmonary embolism (PE) in patients with AECOPD is often difficult due to the similarity in the presenting symptoms of the two conditions. Literature regarding the true prevalence of PE among patients with AECOPD and the role of routine screening for PE in these patients with imaging is controversial. Although some studies have suggested prevalence rates to be as high as 20-25%, thus justifying a routine CT pulmonary angiography (CTPA) to evaluate for PE in these patients, other studies have refuted such findings.

Methods

We used the 2011 Nationwide Inpatient Sample database to identify patients aged ≥18 years admitted with AECOPD (International Classification of Diseases, 9th Revision, Clinical-Modification [ICD-9-CM] code 491.21). Patients with AECOPD with co-existing PE were identified using the ICD-9-CM codes 415.1x and 673.2x. Prevalence of PE in patients with AECOPD was calculated. Similarly, in-hospital mortality, length of stay and mean hospital charge was derived for patient with AECOPD, with and without PE. Statistical analysis was performed using Stata 13.1 (STATA Corp, College Station, TX), which accounted for the complex survey design and clustering of the database.

Results

A total of 1,187,808 admissions with AECOPD were identified, of which 1.18% (n=13,988) patients were found to have co-existent PE. On Univariate analyses, no differences were seen in the demographic characteristics (mean age, sex, race, primary payer, region, bed-size, teaching status) of AECOPD patients with and without PE. However, diagnosis of concurrent PE in patients with AECOPD was associated with higher in-hospital mortality (10.6% vs. 3.81%, p<0.001), mean length of stay (9.38 vs. 5.92 days, p<0.001) and mean total hospital charges ($74,234 vs. 40,424, p<0.001).

Conclusion

In this study of large national database, we found the prevalence of PE in patients admitted for AECOPD to be much lower than reported in literature, suggesting that routine imaging to rule out PE is unlikely to be cost effective. Furthermore, routine screening of AECOPD patients for PE with CTPA might actually result in more untoward effects such as incidental pulmonary nodules and PEs with further unnecessary testing and treatment.