Community-Acquired Pneumonia

General
Facts and Figures
Classification

Presentation
History
Physical Exam
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Radiology

Diagnosis
Criteria for diagnosis
Differential

Microbiology
General
Specific organisms

Pharmacology
Drug Classes
Mechanism of action
Resistance

Treatment
General
Site of care
Medication
Duration
Assessment of response
Prevention

References
Literature cited
Complete bibliography

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Treatment

Site of Care
  • having made the diagnosis of CAP, the 1st step in treatment must assess the severity of illness and a decision made as to whether the patient may be treated as an outpatient or if hospitalization is required

  • it is estimated that approximately 75% of patients with CAP may be treated as outpatients

  • several studies have attempted to identify risk factors that predict increased mortality; Canadian and ATS guidelines defined severe CAP as those cases that included respiratory failure, respiratory rate > 30/min, sepsis or shock, or the presence of extensive infiltrates 20

  • the IDSA guidelines for hospitalization are based on Fine's prediction rule 21 which takes a two-step approach in deciding the appropriate site of care (see IDSA treatment flowchart)

  • according to the rule, patients can be stratified into five risk classes (I-V) using a point system based on 19 variables (Table 5)

    TABLE 5. Prediction model scoring system 22
    Patient characteristics
    Points assigned *
    Demographic factors
    age: males
    age: females
    nursing home resident

    age (in years)
    age (in years) - 10
    +10
    Comorbid illnesses
    neoplastic disease
    liver disease
    congestive heart failure
    cerebrovascular disease
    renal disease

    +30
    +20
    +10
    +10
    +10
    Physical examination findings
    altered mental status
    respiratory rate > 30/min
    SBP < 90 mm Hg
    temperature < 35 C or > 40 C
    pulse > 125/min

    +20
    +20
    +20
    +15
    +10
    Laboratory findings
    pH < 7.35
    BUN > 10.7 mmol/L
    sodium < 130 mEq/L
    glucose > 13.9 mmol/L
    hematocrit < 30
    PO2 < 60 mm Hg**
    pleural effusion

    +30
    +20
    +20
    +10
    +10
    +10
    +10
    * the total risk score is obtained by summing the age in years (age - 10 for females) and the points for each applicable characteristic
    ** oxygen saturation < 90% was also considered abnormal

  • Step 1 attempts to identify patients in Class I by using information obtained from the H&P which is the criteria most commonly available in the primary care setting; this approach is intended to allow a quick assessment of patients who are candidates for outpatient treatment

  • the assessment algorithm in Step 1 considers patient age (> 50 years?), comorbid conditions present (neoplastic disease, CHF, cerebrovascular disease, renal or liver disease?) and physical findings (altered mental status, pulse 125/min, RR 30/min, SBP < 90 mm Hg, temperature < 35 C or 40 C?); a "no" response to all of these questions would place the patient in Class I (Table 6); a reply of "yes" to any of the above would place the patient in Classes II-V and further evaluation based on the above scoring system would be used to determine risk class

    TABLE 6. Stratification of risk score 23
    Risk
    Risk class
    Based on
    Low
    I
    II
    III
    algorithm
    < 70 points
    71-90 points
    Moderate
    IV
    91-130
    High
    V
    > 131

  • patients in Risk Classes I-III have a low risk of mortality (0.1-0.4%, 0.6-0.7%, and 0.9-2.8% respectively) and may be candidates for outpatient care

  • Step 2 uses the scoring chart (Table 5) to stratify patients into risk classes II-V; hospitalization is recommended for patients in classes IV and V; patients in class III may be treated as outpatients or inpatients depending on clinical judgment

  • problems with the prediction model include the possibly time-consuming requirement of calculating a score based on 19 variables and the fact that social factors, which often make outpatient care impractical, are not considered

  • the prediction model is intended to be used as an aid in deciding site of care but is not meant to replace clinical judgment




Footnotes:

20) Mandell LA, Community-acquired pneumonia: etiology, epidemiology, and treatment, Chest, 1995, 108:35S-42S.

21) Fine MJ, et al., A prediction rule to identify low-risk patients with community-acquired pneumonia, NEJM, 1997 Jan 23, 336(4):243-50.

22) Fine MJ, et al., A prediction rule to identify low-risk patients with community-acquired pneumonia, NEJM, 1997 Jan 23, 336(4):243-50.

23) Fine MJ, et al., A prediction rule to identify low-risk patients with community-acquired pneumonia, NEJM, 1997 Jan 23, 336(4):243-50.

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