The evidence about the safety and effectiveness of outpatient care as opposed to inpatient care in selected low–risk patients with acute pulmonary embolism (PE) is accumulating. Most patients enter or remain in the hospital for initial therapy, though some patients may be suitable for partial or complete outpatient management. The Pulmonary Embolism Severity Index (PESI) is an externally validated clinical prediction rule that reliably identifies mortality and other adverse medical outcomes and could potentially supplement physicians’ clinical judgment to guide early discharge decisions. We aimed to explore the potential correlation between the PESI score and the length of stay for patients with acute Pulmonary embolism.


We conducted a retrospective study. Two hundred patients with a diagnosis of PE in 2011 were identified using ICD 9 code. The PESI score was calculated and the patients were categorized into 5 classes accordingly. Class I and II were considered low risk group and class III, IV and V were considered high risk group per previous literature. The Spearman coefficient was used to compare the mean length of stay between class I, II, III, IV and V. Wilcoxon rank sum test was used to compare the mean length of stay between low and high risk groups. The Spearman correlation coefficient and wilcoxon tests were used instead of the more standard Pearson correlation coefficient and paired student t test respectively because of the non–normal distributions of the PESI risk class and length of stay.


The mean length of stay in patients with PESI class I, II, III, IV and V was 4.0, 4.7, 5.6, 6.1 and 7.0 days respectively with a correlation coefficient of +0.268 (P < 0.001). Mean length of stay in patients with a low risk PESI score was 4.4 days compared to 6.1 days in patients with a high score (P < 0.001).


The length of stay for patients with acute PE seems to be associated with the PESI score suggesting that clinicians may intuitively risk stratify patients for earlier discharge. Routine use of the PESI score offers a formal way to risk stratify patients admitted with PE for early hospital discharge and tends to correlate with clinical practice.