Late Rehospitalization and Comorbidity After Treatment for Non-Massive Pulmonary Embolism: An Analysis From the National Readmissions Database

Background
Acute pulmonary embolism (PE) is a common and fatal disease. Non-massive PE (e.g., low-risk and submassive) contributes to the majority of PE cases, although the frequency and causes of late readmission are underreported.

Methods
Using samples from the Nationwide Readmissions Database (NRD) from 2010-2015, patients admitted with non-massive PE were identified using relevant ICD-9 codes. As the NRD resets annually, and in order to capture readmissions into late follow-up, primary hospitalizations for non-massive PE that occurred from January to March in each calendar year allowed for at least 270 days of follow-up to screen for readmission. The rates and causes of readmission were then categorized at < 30 days, 30-90 days, 90-180 days, and > 180 days.

Results
A total of 107,800 patients met inclusion criteria, including 33,410 (31%) that were readmitted within 270 days and 74,390 (69%) had no readmission. Readmitted patients tended to be older [65.0 ± 16.6 vs 61.9 ± 16.9 years, (P < .001], female [56.4% and 52.2%, (P <.001)], had a longer initial mean length of hospital stay [6.0 ± 5.6 and 5.0 ± 4.3 days, (P < .001)]; and higher Charlson Comorbidity Index [1.7 ± 1.3 and 1.1 ± 1.2, (P < .001)]. The mean time to readmission after PE was 71 ± 74 days. The rates of readmission at < 30 days, 30-90 days, 90-180 days, and > 180 days were 43.9%, 26.1%, 18.6%, and 11.3%, respectively. The most common cause of rehospitalization across all four follow-up intervals was pulmonary heart disease, accounting for 14.85%, 6.37%, 5.37%, and 8.85%, respectively.

Conclusions
Nearly one-third of patients treated for non-massive PE are rehospitalized within 9 months, and many readmissions occur beyond 1 month. Chronic pulmonary heart disease is commonly associated with PE rehospitalization into all intervals of early and late follow-up. Further study is required to determine whether intensity of treatment for index non-massive PE reduces rates of rehospitalization. Future prospective studies may also consider monitoring for readmission beyond 30 days to account for late pulmonary comorbidity associated with the condition.