Prognosis is determined by 3 major factors: age of the patient, general state of health (presence of comorbidities), and the setting where antibiotic treatment is given. In general, the mortality rate in outpatients is <1%, while for hospitalized patients, mortality rate ranges from 5% to 15%, but increases to between 20% and 50% in patients requiring intensive care unit admission.[32]Torres A, Peetermans WE, Viegi G, et al. Risk factors for community-acquired pneumonia in adults in Europe: a literature review. Thorax. 2013 Nov;68(11):1057-65.
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[168]Luna HI, Pankey G. The utility of blood culture in patients with community-acquired pneumonia. Ochsner J. 2001 Apr;3(2):85-93.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116772
http://www.ncbi.nlm.nih.gov/pubmed/21765724?tool=bestpractice.com
Several risk factors, such as bacteremia, intensive care unit admission, comorbidities (especially neurological disease), and infection with a potentially multidrug-resistant pathogen (e.g., Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacteriaceae), are associated with increased 30-day mortality.[37]Cillóniz C, Polverino E, Ewig S, et al. Impact of age and comorbidity on cause and outcome in community-acquired pneumonia. Chest. 2013 Sep;144(3):999-1007.
http://www.ncbi.nlm.nih.gov/pubmed/23670047?tool=bestpractice.com
[169]Torres A, Cillóniz C, Ferrer M, et al. Bacteraemia and antibiotic-resistant pathogens in community acquired pneumonia: risk and prognosis. Eur Respir J. 2015 May;45(5):1353-63.
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[170]Sligl WI, Marrie TJ. Severe community-acquired pneumonia. Crit Care Clin. 2013 Jul;29(3):563-601.
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[171]Melzer M, Welch C. 30-day mortality in UK patients with bacteraemic community-acquired pneumonia. Infection. 2013 Oct;41(5):1005-11.
http://www.ncbi.nlm.nih.gov/pubmed/23703286?tool=bestpractice.com
Readmission rates in patients with CAP range from 7% to 12%.[172]Jasti H, Mortensen EM, Obrosky DS, et al. Causes and risk factors for rehospitalization of patients hospitalized with community-acquired pneumonia. Clin Infect Dis. 2008 Feb 15;46(4):550-6.
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[173]Capelastegui A, España Yandiola PP, Quintana JM, et al. Predictors of short-term rehospitalization following discharge of patients hospitalized with community-acquired pneumonia. Chest. 2009 Oct;136(4):1079-85.
http://www.ncbi.nlm.nih.gov/pubmed/19395580?tool=bestpractice.com
In most cases, exacerbation of comorbidities (mainly cardiovascular, pulmonary, or neurological disease) is responsible for readmission.
Prognostic biomarkers such as pro-adrenomedullin, prohormone forms of atrial natriuretic peptide, cortisol, procalcitonin, and C-reactive protein are being studied as predictors of mortality; however, further studies are required before these biomarkers are used for this function in clinical practice.[174]Viasus D, Del Rio-Pertuz G, Simonetti AF, et al. Biomarkers for predicting short-term mortality in community-acquired pneumonia: a systematic review and meta-analysis. J Infect. 2016 Mar;72(3):273-82.
http://www.ncbi.nlm.nih.gov/pubmed/26777314?tool=bestpractice.com
A new screening tool, the quick Sequential Organ Failure Assessment (qSOFA), has been used to identify patients with infections who are at high risk of death. A meta-analysis found that a qSOFA score of 2 or greater has been strongly associated with mortality in patients with pneumonia; however, this score has poor sensitivity and further studies are required.[175]Jiang J, Yang J, Jin Y, et al. Role of qSOFA in predicting mortality of pneumonia: a systematic review and meta-analysis. Medicine (Baltimore). 2018 Oct;97(40):e12634.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6200542
http://www.ncbi.nlm.nih.gov/pubmed/30290639?tool=bestpractice.com