Incidence of Pneumonia

The incidence of pneumonia varies by region, season, and population characteristics. The annual frequency of pneumonia is estimated at 15.1 per 1000 person-years.1 Children under five and adults aged over 65 years are most commonly affected, and the incidence of CAP is also higher in males than females.2

Index Pneumonia Cases Per 1000 Person-Years by Age Group (2008–2014)1

 

CAP Epidemiology index graph

Figure adapted from Tong S, Amand C, Kieffer A, Kyaw MH. Trends in healthcare utilization and costs associated with pneumonia in the United States during 2008-2014. BMC Health Serv Res. 2018;18(1):715 under the Creative Commons Attribution License (CC BY) [https://creativecommons.org/licenses/by/4.0/]

Hospitalization Rates

Between 40% and 60% of patients who present to the emergency department with CAP are admitted.6 Hospitalization and mortality rates increase with older populations and patients with certain comorbidities.4,7 The overall rate of CAP hospitalizations is 634 per 100,000 adults.4

The Impact of Age and Comorbid Conditions on the Incidence of CAP Hospitalization4

Hospitalization for CAP Increases with Certain Comorbid Conditions

Rate of hospitalization in patients with certain comorbid conditions:

  • In obese patients: 674 per 100,000 adults
  • In current smokers: 822 per 100,000 adults
  • In patients with diabetes: 1,808 per 100,000 adults
  • In stroke patients: 2,304 per 100,000 adults
  • In CHF patients: 3,456 per 100,000 adults

 

  • The highest rate of hospitalization for CAP occurs in patients with CHF (3,456 per 100,000 adults) and COPD (5,832 per 100,000 adults)

Hospitalization for CAP Increases with Age

Rate of hospitalizations by age:

  • Aged 18–24 years: 69 per 100,000 adults
  • Aged 25–34 years: 123 per 100,000 adults
  • Aged 35–44 years: 228 per 100,000 adults
  • Aged 45–54 years: 376 per 100,000 adults
  • Aged 60–64 years: 898 per 100,000 adults
  • Aged 75–85 years: 2,205 per 100,000 adults

 

  • The highest rate of hospitalization for CAP occurs in patients aged ≥85 years, occurring at a rate of 3,951 per 100,000 adults

CAP Mortality

CAP is a substantial cause of morbidity and mortality in the US. Together with influenza, pneumonia was the ninth leading cause of death in the USA in 2020, and was associated with a mortality rate of 17.1 deaths per 100,000 individuals.3 Placed in context, mortality for patients with CAP is higher than for those with other infections and patients who are admitted into hospital for other reasons, after adjusting for important variables.2 

 

Patients who do not require hospitalization have a lower mortality rate, of less than 1%. Short-term mortality (30-day) for hospitalized patients ranges from 4% to 18%; however, for patients in intensive care, this rate can reach 50%.2 One third of hospitalized patients will die within 1 year of their inpatient stay.4 Predictors of long-term mortality include age, comorbidities, frailty, cardiovascular complications, inflammation and the severity of the initial insult.2

Learn about the symptoms and diagnosis of CAP

Economic Impact

Pneumonia remains a disease with significant burden in the US, and clinical and economic outcomes vary widely by age.5 The overall US burden of CAP is high, with an estimated 4 million cases of pneumonia reported yearly, resulting in significant healthcare resource spending and lost productivity. More than 10 million physician visits and 64 million days of restricted activity have been attributed to CAP.5 As a leading infectious cause of hospitalizations and a key driver of antibiotic prescribing, CAP is a major burden on the healthcare system. Over 1.5 million unique adults are hospitalized annually,4 resulting in significant healthcare resource spending and lost productivity.

 

The economic burden associated with CAP is substantial and is estimated to exceed more than $17 billion annually in the US; this cost is largely driven by hospital care, particularly for elderly patients.8

 

The rate of hospitalization for treatment failure and the cost of treating CAP are increased for infections that are resistant to antibiotics,9 with available data indicating that Streptococcus pneumoniae isolates are resistant to one or more antibiotics.10 It has been reported that rates of resistance to macrolides increased to ≥25% in the US from 2001 to 2005 and extrapolation suggests that costs of initial treatment failure increase in line with this increase in macrolide resistance.9

Key Epidemiological Data

 

Morbidity

  • ~1.6 million hospitalizations per year11
  • Risk of hospitalization increases with age (>30% of patients aged over 75 years are hospitalized)1
  • Common comorbidities include chronic cardiac disease, chronic pulmonary disease and diabetes 4,12,13

Incidence

  • Incidence: 15.1 per 1000 person years1
  • Eighth leading cause of death, together with influenza3
  • Mean length of hospital stay is over five days8

Hospital Admissions

  • 10–20% of hospitalized patients are admitted to ICU4,8
  • 30-day readmission rates up to 20%2,8
  • All-cause 30-day mortality in hospitalized patients exceeds 10%2,8,14-16
Learn more about the treatment of CAP
Learn about the current treatment challenges in CAP

References

  1. Tong S, Amand C, Kieffer A, et al. Trends in healthcare utilization and costs associated with pneumonia in the United States during 2008–2014. BMC Health Serv Res. 2018;18(1):715.
  2. Prina E, Ranzani OT, Torres A. Community-acquired pneumonia. Lancet. 2015;386(9998):1097–1108.
  3. Ahmad FB, et al. MMWR Morb Mortal Wkly Rep 2021;70:519–22 
  4. Ramirez JA, Wiemken TL, Peyrani P, et al. Adults hospitalized with pneumonia in the United States: Incidence, epidemiology, and mortality. Clin Infect Dis. 2017;65(11):1806–1812.
  5. Park H, Adeyemi AO, Rascati KL. Direct medical costs and utilization of health care services to treat pneumonia in the United States: An analysis of the 2007-2011 Medical Expenditure Panel Survey. Clin Ther. 2015;37(7):1466–1476.e1461.
  6. Wunderink RG, Waterer GW. Clinical practice. Community-acquired pneumonia. N Engl J Med. 2014;370(6):543–551.
  7. Jain S, Self WH, Wunderink RG, et al. Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults. N Engl J Med. 2015;373(5):415–427.
  8. File TM, Jr., Marrie TJ. Burden of community-acquired pneumonia in North American adults. Postgrad Med. 2010;122(2):130–141.
  9. Haran JP, Volturo GA. Macrolide Resistance in Cases of Community-Acquired Bacterial Pneumonia in the Emergency Department. J Emerg Med. 2018;55(3):347–353.
  10. Centers for Disease Control and Prevention. Antibiotic resistance threats in the United States 2019. Available from: https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf  (accessed October 09 2020).
  11. Shoar S, Musher DM. Etiology of community-acquired pneumonia in adults: a systematic review. Pneumonia (Nathan). 2020;12:11.
  12. Fry AM, Shay DK, Holman RC, et al. Trends in hospitalizations for pneumonia among persons aged 65 years or older in the United States, 1988-2002. JAMA. 2005;294(21):2712–2719.
  13. Tillotson G, Lodise T, Classi P, et al. Antibiotic Treatment Failure and Associated Outcomes Among Adult Patients With Community-Acquired Pneumonia in the Outpatient Setting: A Real-world US Insurance Claims Database Study. Open Forum Infect Dis. 2020;7(3):ofaa065.
  14. Violi F, Cangemi R, Falcone M, et al. Cardiovascular complications and short-term mortality risk in community-acquired pneumonia. Clin Infect Dis. 2017;64(11):1486–1493.
  15. Metersky ML, Waterer G, Nsa W, et al. Predictors of in-hospital vs postdischarge mortality in pneumonia. Chest. 2012;142(2):476–481.
  16. Johnstone J, Eurich DT, Majumdar SR, et al. Long-term morbidity and mortality after hospitalization with community-acquired pneumonia: a population-based cohort study. Medicine (Baltimore). 2008;87(6):329–334.
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