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    RAPID Score for Pleural Infection

    Predicts mortality in patients with pleural infection.
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    INSTRUCTIONS

    Use in patients with confirmed pleural infection.

    When to Use
    Pearls/Pitfalls
    Why Use

    Patient with pleural infection, defined by the presence of at least one of the following:

    • Purulent fluid.
    • Positive bacterial culture in fluid.
    • Positive result for bacteria on Gram staining in fluid.
    • Fluid pH <7.2, measured using a blood gas analyzer.
    • Based on trials done in the UK only, so extrapolation to different populations may not be accurate.
    • Although technically externally validated by MIST2, this was not the intended purpose of the study. A large prospective validation study for RAPID is underway.
    • Although the score seems to be able to reliably stratify patients into low, moderate and high risk categories, there is no clear indication for changing treatment exists yet.
    • Purulence confers decreased mortality, which is counter to some other studies. The authors observed that purulent collections were less likely to have loculations and were therefore more amenable to complete drainage.
    • Pleural infection is a common condition with a high mortality with rising incidence in both adult and pediatric populations.
    • Treatment options vary from very invasive, such as thoracic surgery, to simple treatment with antibiotics and/or intrapleural fibrinolytics.
    • Determining which therapeutic approach is best for each patient can be challenging, as can predicting which patients are most likely to need extended stays in hospital.
    • The RAPID Score is a robustly-developed risk model which has the potential to allow treatments to be more effectively targeted in pleural infection patients.
    <14 mg/dL (5 mmol/L)
    0
    14–23 mg/dL (5–8 mmol/L)
    +1
    >23 mg/dL (8 mmol/L)
    +2
    <50
    0
    50-70
    +1
    >70
    +2
    Yes
    0
    No
    +1
    Community-acquired
    0
    Hospital-acquired
    +1
    ≥2.7 g/dL (27 g/L)
    0
    <2.7 g/dL (27 g/L)
    +1

    Result:

    Please fill out required fields.

    Next Steps
    Evidence
    Creator Insights

    Advice

    Factors associated with high risk scores include gram-negative rod infections, heart disease, diabetes, cancer, lung disease, and increased length of stay. Consider erring on the side of caution in patients with these.

    Management

    • It is not yet known how best to manage patients based on RAPID Score; however:
      • Patients who are low risk may be better candidates for invasive surgical therapy, including thoracotomy or video-assisted thoracoscopic surgery (VATS).
      • Some higher risk patients may benefit from earlier aggressive intervention to minimize the chances of poor outcomes.
      • Higher risk patients who are sicker at presentation may be better suited for less invasive therapies like tube thoracostomy and fibrinolytics.
    • Knowledge of the RAPID Score may help physicians advise patients and family members regarding the likely duration of stay in hospital and, if appropriate, their risk of mortality.

    Critical Actions

    • The RAPID Score has yet to be prospectively validated in a large trial setting and so its role in routine clinical care is not fully formed.
    • Clinical decisions regarding the treatment of pleural infection must always be taken with local variability in mind, especially relating to the availability of thoracic surgery and knowledge of likely causative organisms.
    • The RAPID Score does not dictate treatment, but rather gives better information about the patient at presentation.

    Formula

    Addition of the selected points:

     

    Points

    0

    1

    2

    Serum BUN (urea)

    <14 mg/dL (5 mmol/L)

    14–23 mg/dL (5–8 mmol/L)

    >23 mg/dL

    (8 mmol/L)

    Age, years

    <50

    50–70

    >70

    Purulent pleural fluid

    Yes

    No

    --

    Infection source

    Community-acquired

    Hospital-acquired

    --

    Serum albumin

    ≥2.7 g/dL (27 g/L)

    <2.7 g/dL (27 g/L)

    --

    Note: RAPID = Renal, Age, Purulence, Infection source, and Dietary factors.

    Facts & Figures

    Interpretation:

    RAPID Score

    Risk

    3-month mortality*

    0–2

    Low

    1.5%

    3–4

    Medium

    17.8%

    5–7

    High

    47.8%

    *From validation study, White 2015.

    Evidence Appraisal

    The RAPID Score was derived from a large cohort of patients in the MIST1 randomized controlled trial, which determined that there was no role for isolated fibrinolytic (streptokinase) use in pleural infection. It was then validated using data from  a second cohort in the smaller MIST2 study. This important RCT determined that combination tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) was the most effective treatment for those with pleural infection requiring tube drainage. Applying the score to the MIST2 group showed a similar separation in 3-month survival between the low, moderate and high-risk groups of patients enrolled into the study.

    A potential criticism of this approach is that enrollment criteria for RCTs are often not representative of the general population, and so a score derived from such studies would be limited in its use. The authors found no clear signal predicting the need for surgery at three months.

    Subsequently, the RAPID Score was retrospectively assessed in a “real-world” population by White et al (2015). Their data once again demonstrated clear delineation between the three outcome groups, lending further weight to the validity of the RAPID Score. However, their population only included patients with culture-positive disease. Only 32% of patients in the MIST2 cohort were culture positive, the rest being diagnosed by alternative means. It is possible that patients with culture-positive fluid fare worse than those without, which would affect the results of this study. In addition, 25% of patients had missing data.

    The PILOT study (ISRCTN50236700) was designed specifically to prospectively assess the RAPID Score. It recently finished recruitment of over 500 patients in 5 countries across 3 continents, and results are being awaited.

    Dr. Najib M. Rahman

    About the Creator

    Najib M. Rahman, BM BCh, PhD, is a consultant and senior lecturer in respiratory medicine in the Nuffield Department of Medicine in Oxford, United Kingdom. His research interests are in pleural infection and pleural malignancy. Dr. Rahman leads pleural trials and trials methodology at the Oxford Respiratory Trials Unit (ORTU).

    To view Dr. Najib M. Rahman's publications, visit PubMed

    Content Contributors
    • Rahul Bhatnagar, MBChB
    About the Creator
    Dr. Najib M. Rahman
    Content Contributors
    • Rahul Bhatnagar, MBChB