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

• Published in: Open Forum Infectious Diseases
• Main Authors: Bjarnason, Agnar, Westin, Johan, Lindh, Magnus, Andersson, Lars-Magnus, Kristinsson, Karl G., Löve, Arthur, Baldursson, Ólafur, Gottfredsson, Magnus
• Other Authors: Læknadeild (HÍ), Faculty of Medicine (UI), Heilbrigðisvísindasvið (HÍ), School of Health Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2018
• Subjects: Community acquired pneumonia; Etiology; Incidence; Mycoplasma pneumoniae; Streptococcus pneumoniae; Lungnabólga; Algengi sjúkdóma; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/750; https://doi.org/10.1093/ofid/ofy010

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. This work was funded by the Icelandic Center for Research, Rannís (grant number 100436021), the Landspitali University Hospital Science Fund, and the University of Iceland Research Fund. ...