Chest
Volume 145, Issue 4, April 2014, Pages 848-855
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Original Research: Disorders of the Pleura
A Clinical Score (RAPID) to Identify Those at Risk for Poor Outcome at Presentation in Patients With Pleural Infection

https://doi.org/10.1378/chest.13-1558Get rights and content

Background

Pleural infection is associated with a high morbidity and mortality. Development of a validated clinical risk score at presentation to identify those at high risk of dying would enable patient triage and may help formulate early management strategies.

Methods

A clinical risk score was derived based on data from patients entering the multicenter UK pleural infection trial (first Multicenter Intrapleural Sepsis Trial [MIST1], n = 411). From 22 baseline clinical characteristics, model selection was undertaken to find variables predictive of poor clinical outcome. Outcomes were mortality at 3 months (primary), need for surgical intervention at 3 months, and time from randomization to discharge. The derived scoring system RAPID (renal, age, purulence, infection source, and dietary factors) was validated using patients enrolled in the subsequent MIST2 trial (n = 191).

Results

Age, urea, albumin, hospital-acquired infection, and nonpurulence predicted poor outcome. Patients were stratified into low-risk (0-2), medium-risk (3-4), and high-risk (5-7) groups. Using the low-risk group as a reference, a RAPID score of 3 to 4 and > 4 was associated with an OR of 24.4 (95% CI, 3.1-186.7; P = .002) and 192.4 (95% CI, 25.0-1480.4; P < .001), respectively, for death at 3 months. In the validation cohort (MIST2), a medium-risk RAPID score was nonsignificantly associated with mortality (OR, 3.2; 95% CI, 0.8-13.2; P = .11), and a high-risk score was associated with increased mortality (OR, 14.1; 95% CI, 3.5-56.8; P < .001). Hospitalization duration was associated with increasing RAPID score (score 0-2: median duration = 7, interquartile range 6-13; score > 5: median duration = 15, interquartile range 9-28, P = .08).

Conclusions

The RAPID score may permit risk stratification of patients with pleural infection at presentation.

Section snippets

Materials and Methods

This study used data from two randomized trials of intrapleural agents for the treatment of pleural infection10, 28 diagnosed according to identical and standard clinical criteria (described here). The initial model derivation was conducted using baseline clinical and outcome data from the first Multicenter Intrapleural Sepsis Trial (MIST1) (ISRCTN39138989),10 a placebo-controlled randomized trial assessing the use of intrapleural streptokinase that recruited 454 patients from 54 UK centers

Patients and Data Completeness

The trial flowchart combining patients from both studies is presented in Figure 1. The baseline demographic, clinical, and microbiologic characteristics of participants in the combined trial populations and degree of data completeness for the purpose of this study are presented in Table 1. Mortality at 3-month data (primary outcome) were available in 617 of 621 patients (99%), and secondary outcomes (surgery at 3 months and hospital stay from randomization) were available in 614 of 621 patients

Discussion

To our knowledge, this is the first prognostic risk model for patients with pleural infection derived from data obtained from one cohort that has then been validated in a second cohort. Of 22 baseline characteristics recorded at the time of initial presentation, five were strongly independently associated with poor outcome.

The risk model developed gave more weighting to both age and urea in light of their high ORs for mortality, with the other three variables scoring the same. Each patient's

Acknowledgments

Author contributions: Dr Rahman is guarantor for the entire manuscript.

Dr Rahman: contributed to study conception and design, writing and revision of the manuscript, and approval of the submitted version of the manuscript.

Mr Kahan: contributed to conducting the statistical analysis, writing and revision of the manuscript, and approval of the submitted version of the manuscript.

Prof Miller: contributed to the writing and revision of the manuscript and approval of the submitted version of the

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    Funding/Support: Drs Rahman and Gleeson are funded by the UK NIHR Oxford Biomedical Research Centre Programme. Dr Maskell is funded by a Clinical Senior Lectureship Higher Education Funding Council for England/United Kingdom Clinical Research Collaboration award.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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