Clinical Evidence Handbook

A Publication of BMJ Publishing Group

Community-Acquired Pneumonia
MARK LOEB, McMaster University, Hamilton, Canada

This is one in a series of

chapters excerpted from
In the northern hemisphere, about 12 out • Pneumococcal vaccine is unlikely to
of 1,000 persons per year (on average) con- reduce all-cause pneumonia or mortality in
the Clinical Evidence
Handbook, published by tract pneumonia while living in the commu- immunocompetent adults, but may reduce
the BMJ Publishing Group, nity, with most cases caused by Streptococcus pneumococcal pneumonia in this group.
London, U.K. The medical pneumoniae. Antibiotics lead to clinical cure in at
information contained
herein is the most accurate • Persons at greatest risk include those at least 80 percent of persons with pneumonia
available at the date of the extremes of age, smokers, those who are being treated in the community or hospital,
publication. More updated alcohol-dependent, and those with lung or although no one regimen has been shown to
and comprehensive infor- heart disease or immunosuppression. be superior to the others in either setting.
mation on this topic may
be available in future print • Mortality ranges from about 5 to 35 • Early mobilization may reduce hospital
editions of the Clinical Evi- percent, depending on severity of disease, stay compared with usual care in persons
dence Handbook, as well with a worse prognosis in older persons, being treated with antibiotics.
as online at http://www.
clinicalevidence.bmj.com
men, and persons with chronic diseases. • Intravenous antibiotics have not been
(subscription required). Deaths from influenza are usually caused shown to improve clinical cure rates or
Those who receive a by pneumonia. Influenza vaccine reduces survival compared with oral antibiotics in
complimentary print copy the risk of clinical influenza, and may reduce persons treated in the hospital for nonsevere,
of the Clinical Evidence the risk of pneumonia and mortality in older community-acquired pneumonia.
Handbook from United
Health Foundation can persons. Prompt administration of antibiotics may
gain complimentary online
access by registering on
the Web site using the
ISBN number of their book. Clinical Questions

What are the effects of interventions to prevent community-acquired pneumonia?

This clinical content con-
Likely to be beneficial Influenza vaccine (in older persons)*
forms to AAFP criteria for
evidence-based continu- Unlikely to be beneficial Pneumococcal vaccine (for all-cause pneumonia and mortality in
ing medical education immunocompetent adults)
(EB CME). See CME Quiz What are the effects of treatments for community-acquired pneumonia in outpatient
on page 171. settings?
A collection of Clinical Likely to be beneficial Antibiotics (compared with no antibiotics)*
Evidence Handbook pub- What are the effects of treatments for community-acquired pneumonia in persons
lished in AFP is available admitted to a hospital?
at http://www.aafp.org/ Likely to be beneficial Antibiotics (compared with no antibiotics)*
afp/bmj.
Early mobilization (may reduce hospital stay compared with usual care)*
Unlikely to be beneficial Intravenous antibiotics in immunocompetent persons in a hospital
without life-threatening illness (compared with oral antibiotics)
What are the effects of treatments in persons with community-acquired pneumonia
receiving intensive care?
Likely to be beneficial Prompt administration of antibiotics in persons admitted to intensive care
with community-acquired pneumonia (improved outcomes compared
with delayed antibiotic treatment)*
Unknown effectiveness Different combinations of antibiotics in intensive care settings

*—Based on consensus.

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 Clinical Evidence Handbook

improve survival compared with delayed (RR = 3.0; 95% CI, 2.3 to 3.9), heart disease
treatment in persons receiving intensive (RR = 1.9; 95% CI, 1.7 to 2.3), institutional-
care for community-acquired pneumonia, ization (RR = 1.8; 95% CI, 1.4 to 2.4), and
although we found few studies. increasing age (age at least 70 years versus
• We do not know which is the optimum 60 to 69 years; RR = 1.5; 95% CI, 1.3 to 1.7).
antibiotic regimen to use in these persons.
Prognosis
Definition Severity varies from mild to life-threatening
Community-acquired pneumonia is pneu- illness within days of symptom onset. A pro-
monia contracted in the community rather spective cohort study of more than 14,000
than in a hospital. It is defined by clini- persons found that older age was an extremely
cal symptoms (e.g., cough, sputum produc- important factor in determining prognosis.
tion, pleuritic chest pain) and signs (e.g., One systematic review of prognosis studies
fever, tachypnea, rales), with radiologic for community-acquired pneumonia (search
confirmation. date, 1995; 33,148 persons) found overall
mortality to be 13.7 percent, ranging from
Incidence and Prevalence 5.1 percent for ambulatory persons to 36.5
In the northern hemisphere, community- percent for persons who required intensive
acquired pneumonia affects about 12 out of care. Prognostic factors significantly associ-
1,000 persons per year, particularly during ated with mortality were: male sex (odds ratio
winter, and in persons at the extremes of age [OR] = 1.3; 95% CI, 1.2 to 1.4), absence of
(annual incidence in persons younger than pleuritic chest pain (OR = 2.00; 95% CI, 1.25
one year: 30 to 50 out of 1,000; 15 to 45 years to 3.30), hypothermia (OR = 5.0; 95% CI, 2.4
of age: 1 to 5 out of 1,000; 60 to 70 years of to 10.4), systolic hypotension (OR = 4.8; 95%
age: 10 to 20 out of 1,000; 71 to 85 years of CI, 2.8 to 8.3), tachypnea (OR = 2.9; 95% CI,
age: 50 out of 1,000). 1.7 to 4.9), diabetes mellitus (OR = 1.3; 95%
CI, 1.1 to 1.5), neoplastic disease (OR = 2.8;
Etiology 95% CI, 2.4 to 3.1), neurologic disease (OR
More than 100 microorganisms have been = 4.6; 95% CI, 2.3 to 8.9), bacteremia (OR
implicated in community-acquired pneu- = 2.8; 95% CI, 2.3 to 3.6), leukopenia (OR =
monia, but most cases are caused by S. pneu- 2.5; 95% CI, 1.6 to 3.7), and multilobar radio-
moniae. Case-control study data suggest that graphic pulmonary infiltrates (OR = 3.1; 95%
smoking is probably an important risk factor. CI, 1.9 to 5.1).
One large cohort study conducted in Finland
SEARCH DATE: January 2010.
(4,175 persons at least 60 years of age) sug-
gested that risk factors for pneumonia in Author disclosure: Mark Loeb has received research
grants from Bayer and Aventis, and has attended confer-
older persons include alcoholism (relative ences sponsored by Janssen-Ortho and Aventis.
risk [RR] = 9.0; 95% confidence interval
Adapted with permission from Loeb M. Community-
[CI], 5.1 to 16.2), bronchial asthma (RR = acquired pneumonia. Clin Evid Handbook. December
4.2; 95% CI, 3.3 to 5.4), immunosuppression 2010:515-516. Please visit http://www.clinicalevidence.
(RR = 3.1; 95% CI, 1.9 to 5.1), lung disease bmj.com for full text and references. ■

July 15, 2011 ◆ Volume 84, Number 2 www.aafp.org/afp American Family Physician 219