Pulmonary Embolism Severity Index (PESI) Score

PESI explained

The pulmonary embolism severity index (PESI score) stratifies mortality risk in PE (can also be used for morbidity prediction) in 5 severity classes and offers a probability of adverse outcome.

This risk stratification assessment is based on 11 clinical variables that refer to patient status and were found by the original study to be independent predictors of PE mortality.

These are weighted differently depending on the contribution of the variable in the prediction rule.

The following table introduces the 11 variables and the number of points awarded to them.

Result interpretation

The prognosis classification in five severity classes and their associated 30-day mortality risk and probability, can be found in the table below:

Low risk classes, I and II may be considered for outpatient treatment. High risk cases however, classes III, IV and V require higher levels of care, usually in the ICU.

About the study

The PESI was created in 2005 by Aujesky et al. following a study on 15,531 patients diagnosed with PE and treated in 186 Pennsylvania hospitals. 67% of the sample was used in derivation of the index and 33% in validation. The PESI was also externally validated in 221 patients.

The prediction model was derived using logistic regression with 30-day mortality as the primary outcome and with several patient data as potential predictor variables.

11 variables were independently associated with mortality from PE and helped classify patients in five severity classes (described above in result interpretation).

The index was found to be reliable in classifying patients in terms of 30-day mortality risk and can contribute to initial treatment guidance.

Prognosis in PE

PE is a potentially fatal disorder but mortality rates for untreated PE have decreased in time. Prognosis in pulmonary embolism is highly dependent on:

■ The pulmonary area affected;

■ The size and placement of the clot;

■ The existence of other medical conditions;

■ The existence of associated risk factors.

In terms of clot blockage, the bigger the clot and the more important the blood vessel blocked is, the greater the risk of adverse outcome. If the blood clot breaks and enters the lung, death is rapid because the lung cannot provide oxygen to the blood anymore and pressure collapses.

In less severe cases, in hospital treatment with blood thinners is required. Medication is also prescribed for at least 6 months after the episode. For some patients, urgent surgery to apply a clot preventing filter, may be necessary.

Original source

Aujesky D, Obrosky DS, Stone RA, Auble TE, Perrier A, Cornuz J, Roy PM, Fine MJ. Derivation and validation of a prognostic model for pulmonary embolism. Am J Respir Crit Care Med. 2005; 172(8):1041-6.

Validation

Donzé J, Le Gal G, Fine MJ, Roy PM, Sanchez O, Verschuren F, Cornuz J, Meyer G, Perrier A, Righini M, Aujesky D. Prospective validation of the Pulmonary Embolism Severity Index. A clinical prognostic model for pulmonary embolism. Thromb Haemost. 2008; 100(5):943-8.

Other references

1. Aujesky D, Roy PM, Verschuren F, Righini M, Osterwalder J, Egloff M, Renaud B, Verhamme P, Stone RA, Legall C, Sanchez O, Pugh NA, N'gako A, Cornuz J, Hugli O, Beer HJ, Perrier A, Fine MJ, Yealy DM. Outpatient versus inpatient treatment for patients with acute pulmonary embolism: an international, open-label, randomised, non-inferiority trial. Lancet. 2011; 378(9785):41-8.

2. Wicki JPerrier APerneger TVBounameaux HJunod AF. Predicting adverse outcome in patients with acute pulmonary embolism: a risk score. Thromb Haemost 2000; 84 (4) 548 - 552.