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. 2018 Feb 8;5(2):ofy010.
doi: 10.1093/ofid/ofy010. eCollection 2018 Feb.

Incidence, Etiology, and Outcomes of Community-Acquired Pneumonia: A Population-Based Study

Agnar Bjarnason  1   2 , Johan Westin  2   3 , Magnus Lindh  2   3 , Lars-Magnus Andersson  2   3 , Karl G Kristinsson  1   4 , Arthur Löve  1   4 , Olafur Baldursson  4 , Magnus Gottfredsson  1   4
Affiliations

Incidence, Etiology, and Outcomes of Community-Acquired Pneumonia: A Population-Based Study

Agnar Bjarnason et al. Open Forum Infect Dis. .

Abstract

Background: The microbial etiology of community-acquired pneumonia (CAP) is often unclear in clinical practice, and previous studies have produced variable results. Population-based studies examining etiology and incidence are lacking. This study examined the incidence and etiology of CAP requiring hospitalization in a population-based cohort as well as risk factors and outcomes for specific etiologies.

Methods: Consecutive admissions due to CAP in Reykjavik, Iceland were studied. Etiologic testing was performed with cultures, urine-antigen detection, and polymerase chain reaction analysis of airway samples. Outcomes were length of stay, intensive care unit admission, assisted ventilation, and mortality.

Results: The inclusion rate was 95%. The incidence of CAP requiring hospitalization was 20.6 cases per 10000 adults/year. A potential pathogen was detected in 52% (164 of 310) of admissions and in 74% (43 of 58) with complete sample sets. Streptococcuspneumoniae was the most common pathogen (61 of 310, 20%; incidence: 4.1/10000). Viruses were identified in 15% (47 of 310; incidence: 3.1/10000), Mycoplasmapneumoniae were identified in 12% (36 of 310; incidence: 2.4/10000), and multiple pathogens were identified in 10% (30 of 310; incidence: 2.0/10000). Recent antimicrobial therapy was associated with increased detection of M pneumoniae (P < .001), whereas a lack of recent antimicrobial therapy was associated with increased detection of S pneumoniae (P = .02). Symptoms and outcomes were similar irrespective of microbial etiology.

Conclusions: Pneumococci, M pneumoniae, and viruses are the most common pathogens associated with CAP requiring hospital admission, and they all have a similar incidence that increases with age. Symptoms do not correlate with specific agents, and outcomes are similar irrespective of pathogens identified.

Keywords: Mycoplasma pneumoniae; Streptococcus pneumoniae; community-acquired pneumonia; etiology; incidence.

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