Elsevier

Journal of Infection

Volume 60, Issue 2, February 2010, Pages 106-113
Journal of Infection

Review
Validation and comparison of SCAP as a predictive score for identifying low-risk patients in community-acquired pneumonia

https://doi.org/10.1016/j.jinf.2009.11.013Get rights and content

Summary

Purposes

(1) To validate the Severe Community Acquired Pneumonia (SCAP) score in predicting 30-day mortality. (2) To validate its ability to identifying patients at low risk of death. (3) To compare it against the Pneumonia Severity Index (PSI), and the British Thoracic Society's CURB-65 rules.

Methods

The SCAP score was validated to predict 30-day mortality in an internal validation cohort of consecutive adult patients seen in one hospital. Consecutive inpatients from other three hospitals were used to externally validate the score and compare the SCAP with the PSI and CURB-65. The discriminatory power of these rules to predict 30-day mortality was tested by the Area under Curve (AUC), and their predictive accuracy with the sensitivity, specificity and predictive values.

Results

The 30-day mortality rate increased directly with increasing SCAP score (class 0: 0.5%, to class 4: 66.5% risk) in the internal validation cohort, and from 1.3% to 29.2% in external cohort (P < 0.001) with an AUC of 0.83 and 0.75, respectively (P = 0.024). The SCAP score identified 62.4% (95% IC 58.8–66.0) low-risk patients, 52.5% (95% IC 48.8–56.2) the PSI and 46.2% (95% CI 42.5–49.9) the CURB-65 in the external cohort. Patients classified as low risk by the three rules had similar 30-day mortality (SCAP: 2.5%, PSI: 1.6% and CURB-65: 2.7%).

Conclusion

The SCAP is valid to predict 30-day mortality among low-risk patients and identifies a larger proportion of patients as low-risk than the other studied rules.

Introduction

Assessment of disease severity is the starting point in the management algorithm for community-acquired pneumonia (CAP) in both the current European1, 2, 3 and American guidelines.4, 5, 6 The aim is to enhance the appropriateness of admission and to lower unnecessary admission rates, to improve quality of care and safely reduce costs. Two validated tools – the Pneumonia Severe Index (PSI)7 and the Confusion, Urea, Respiratory rate, Blood pressure, and age ≥65 years (CURB-65) scale of the British Thoracic Society8 – have already shown their value in stratifying patients regarding 30-day mortality.

As far as now, the PSI and CURB-65 have been separately validated for 30-day mortality.9, 10, 11, 12, 13, 14, 15 So far, some studies have demonstrated that use of the PSI as to guide the initial site of treatment decision reduces the admission of low-risk patients with CAP without compromising patient outcomes.16, 17 Although this index seems to have been developed as a way to identify patients at low risk of mortality, it can occasionally underestimate severity of illness, especially in young patients without comorbid illness.18 The CURB-65 is simpler than the PSI and more focused on the severity of the CAP episode. However, it appears to be less useful for determining which patients can be safely treated at home.11

We recently developed a clinical prediction rule for severe community-acquired pneumonia, which we call here the SCAP score19 that was better at identifying severe CAP than the PSI and CURB-65.20 However, the SCAP score has not been already validated for predicting 30-day mortality, and its usefulness for identifying patients at low risk is unknown.21

The aim of this study was to: (1) validate in two independent cohorts the accuracy and discriminatory power of the SCAP score in predicting 30-day mortality; (2) evaluate its ability to stratify patients with CAP into different management groups and thereby identify patients at low risk of death who could be candidates for outpatient treatment; and (3) compare, in the external validation cohort, the SCAP score against two other commonly used instruments, the PSI and CURB-65, for the above-mentioned goals.

Section snippets

Methods

This is a prospective cohort study with two cohorts. The project was approved by each of the hospitals' ethics review board.

Results

A total of 2404 patients were enrolled in the internal validation cohort: 1501 inpatients (62.4%) and 903 outpatients (37.6%). The external validation cohort consisted of 712 inpatients (271 at Cruces Hospital in Vizcaya, 288 at La Fe Hospital in Valencia, and 153 at Clinic Hospital in Barcelona). The sociodemographic features of both cohorts are described in Table 1. Comparing the inpatients in these cohorts, those in the internal validation cohort were more likely to be older, live at a

Discussion

Scores on the SCAP, a newly developed prediction rule for patients with CAP were closely correlated with 30-day mortality in two large cohorts of patients with CAP. The SCAP score was more accurate at identifying low-risk patients than the PSI and CURB-65. These findings indicate that the SCAP score can be used to identify patients at low risk of death who may be considered for outpatient care.

The relative utility of the different prediction rules is still being assessed. In a recent study, PSI

Acknowledgments

We appreciate the support of the staff members of the different services.

References (34)

  • M.J. Fine et al.

    A prediction rule to identify low-risk patients with community-acquired pneumonia

    N Engl J Med

    (1997)
  • W.S. Lim et al.

    Defining community-acquired pneumonia severity on presentation to hospital: an international derivation and validation study

    Thorax

    (2003)
  • P.P. España et al.

    A prediction rule to identify allocation of inpatient care in community-acquired pneumonia

    Eur Respir J

    (2003)
  • S.Y. Man et al.

    Prospective comparison of three predictive rules for assessing severity of community-acquired pneumonia in Hong Kong

    Thorax

    (2007)
  • K.L. Buising et al.

    A prospective comparison of severity scores for identifying patients with severe community acquired pneumonia: reconsidering what is meant by severe pneumonia

    Thorax

    (2006)
  • M.R. Ananda-Rajah et al.

    Comparing the pneumonia severity index with CURB-65 in patients admitted with community acquired pneumonia

    Scand J Infect Dis

    (2007)
  • T.J. Marrie et al.

    A controlled trial of a critical pathway for treatment of community-acquired pneumonia. CAPITAL study investigators. Community-acquired pneumonia intervention trial assessing levofloxacin

    JAMA

    (2000)
  • Cited by (26)

    • Clinical Policy: Critical Issues in the Management of Adult Patients Presenting to the Emergency Department With Community-Acquired Pneumonia

      2021, Annals of Emergency Medicine
      Citation Excerpt :

      The severe CAP (SCAP) aid, also known as CURXO-80, was developed by España et al38 in a Class III observational trial of 1,057 patients designed to predict a combined outcome of inhospital mortality, invasive ventilatory support, or use of vasopressors for shock among patients with CAP. It was subsequently externally validated.39 The aid includes 2 major and 6 minor criteria, and it recommends that patients be considered for ICU care if they have at least 1 major or 2 minor criteria.

    • Care of Respiratory Conditions in an Observation Unit

      2017, Emergency Medicine Clinics of North America
      Citation Excerpt :

      One drawback to this score is the use of arterial pH, which is not always measured. In a prospective validation study of the 3 scoring systems—PSI, CURB-65, and SCAP—patients considered low risk by all 3 had similar low risks of mortality.80 All 3 scoring systems had similar but not insignificant rates of inpatients identified as low risk that required intensive care unit admission: PSI (4.8%), CURB-65 (2.8%), and SCAP (2.7%).

    • Performance of pro-adrenomedullin for identifying adverse outcomes in community-acquired pneumonia

      2015, Journal of Infection
      Citation Excerpt :

      We developed a clinical prediction rule for severe CAP, called the severe community-acquired pneumonia (SCAP) score.5 It has been validated for the prediction of mortality in patients at low risk of mortality.6 Some of these instruments have been used to address the challenge of identifying patients with CAP who can be safely treated as outpatients rather than requiring hospitalization,7 and yet there are limited and controversial data regarding whether patients at low risk of dying based on severity criteria require admission to hospital.8

    • Correlation of inflammatory and cardiovascular biomarkers with pneumonia severity scores

      2014, Enfermedades Infecciosas y Microbiologia Clinica
      Citation Excerpt :

      Although these rules can be useful for the management of patients with pneumonia, they also present some disadvantages such as age overemphasis and complexity for its calculation. In the last years, two other severity scores have been defined: severe CAP (SCAP) that was developed for identifying patients who are at risk for an adverse outcome and might need ICU admission, being as accurate as current scoring systems3–5 and SMART-COP, mainly designed for the prediction of patients that are likely to require intensive respiratory or vasopressor support (IRVS).6 Main drawbacks for these last scores are the lack of consideration for the presence of comorbidities and the need of more testing and validation, although results from a recent meta-analysis indicate their usefulness for the prediction of ICU admission or intensive treatment in patients with CAP.7

    • Defining severe pneumonia

      2011, Clinics in Chest Medicine
      Citation Excerpt :

      The IDSA/ATS 20075 guidelines include new predictors that are in the process of validation with reasonable performance.52,65–67 Other models specific to SCAP have been developed, including a recent Australian model called SMART-COP,51 a Spanish model called CURXO (although the investigators of this prediction model designate it SCAP, the authors find this usage confusing because the score is designed to predict SCAP but is one of several competing prediction models; the authors therefore refer to it as CURXO),68–70 and a mixed French-American score called the REA-ICU index.71 The SMART-COP, which predicts mechanical ventilation or vasopressors, has been externally validated in patients younger than 50 years.72

    View all citing articles on Scopus
    View full text