Systolic Blood Pressure is Superior to Other Haemodynamic Predictors of Outcome in Community Acquired Pneumonia

James D Chalmers ^1*, Aran Singanayagam ¹ and Adam T Hill ¹

¹ Royal Infirmary of Edinburgh, Edinburgh., United Kingdom

^* To whom correspondence should be addressed. E-mail: jamesdchalmers{at}googlemail.com.

Accepted 23 April 2008

Abstract

Introduction: Admission blood pressure assessment is a central component of severity assessment for community acquired pneumonia. The aim of this study was to establish which readily available haemodynamic measure on admission is most useful for predicting severity in patients admitted with community acquired pneumonia.

Methods: A prospective observational study of patients admitted with community acquired pneumonia was conducted in Edinburgh, UK. The measurements compared were systolic and diastolic blood pressure, mean arterial pressure and pulse pressure. The outcomes of interest were 30-day mortality and the requirement for mechanical ventilation and/or inotropic support.

Results: Admission systolic BP <90mmHg, diastolic BP < 60mmHg, mean arterial pressure <70mmHg and pulse pressure <40mmHg were all associated with increased 30-day mortality and the need for mechanical ventilation and/or inotropic support on multivariate logistic regression. The AUC for each predictor of 30-day mortality was as follows: systolic BP <90mmHg 0.70; diastolic BP < 60mmHg 0.59; mean arterial pressure 0.64; pulse pressure < 40mmHg 0.60. The AUC for each predictor of need for mechanical ventilation and/or inotropic support were as follows: systolic BP <90mmHg 0.70; diastolic BP < 60mmHg 0.68; mean arterial pressure 0.69; pulse pressure < 40mmHg 0.59. A simplified CRB65 score containing systolic blood pressure <90mmHg alone performed equally well to standard CRB65 score (AUC 0.76 vs 0.74) and to the standard CURB65 score (0.76 vs 0.76) for the prediction of 30-day mortality. The simplified CRB65 score was equivalent for prediction of mechanical ventilation and/or inotropic support to standard CRB65 (0.77 vs 0.77) and to CURB65 (0.77 vs 0.78).

Conclusion: Systolic blood pressure is superior to other haemodynamic predictors of 30-day mortality and need for mechanical ventilation and/or inotropic support in community acquired pneumonia. The CURB65 score can be simplified to a modified CRB65 score by omission of the diastolic blood pressure criterion without compromising its accuracy.