Age-stratified burden of pneumococcal community acquired pneumonia in hospitalised Canadian adults from 2010 to 2015

Abstract

Background: In Canada, 13-valent pneumococcal conjugate vaccine (PCV13) is recommended in childhood, in individuals at high risk of invasive pneumococcal disease (IPD) and in healthy adults aged ≥65 years for protection against vaccine-type IPD and pneumococcal community-acquired pneumonia (pCAP). Since vaccine recommendations in Canada include both age-based and risk-based guidance, this study aimed to describe the burden of vaccine-preventable pCAP in hospitalised adults by age.

Methods: Surveillance for community-acquired pneumonia (CAP) in hospitalised adults was performed prospectively from 2010 to 2015. CAP was radiologically confirmed, and pCAP was identified using blood and sputum culture and urine antigen testing. Patient demographics and outcomes were stratified by age (16-49, 50-64, ≥65 and ≥50 years).

Results: Of 6666/8802 CAP cases tested, 830 (12.5%) had pCAP, and 418 (6.3%) were attributed to a PCV13 serotype. Of PCV13 pCAP, 41% and 74% were in adults aged ≥65 and ≥50 years, respectively. Compared with non-pCAP controls, pCAP cases aged ≥50 years were more likely to be admitted to intensive care units (ICUs) and to require mechanical ventilation. Older adults with pCAP were less likely to be admitted to ICU or required mechanical ventilation, given their higher mortality and goals of care. Of pCAP deaths, 67% and 90% were in the ≥65 and ≥50 age cohorts, respectively.

Conclusions: Adults hospitalised with pCAP in the age cohort of 50-64 years contribute significantly to the burden of illness, suggesting that an age-based recommendation for adults aged ≥50 years should be considered in order to optimise the impact of pneumococcal vaccination programmes in Canada.

Keywords: adult; burden; community-acquired pneumonia (CAP); pneumococcal vaccine, PCV13, ageStreptococcus pneumoniae; serotype.

Figure 1

Laboratory testing for Streptococcus pneumoniae in cap cases and proportion of cap identified as pCAP by age. (A) Proportion by age of cap cases tested for S. pneumoniae using ssUAD, BC, SC, at least one (any) diagnostic test or all diagnostic tests. (B) Proportion by age of cap cases identified as pCAP for each laboratory method or testing combinations. BC, blood culture; CAP, community-acquired pneumonia; pCAP, pneumococcal community-acquired pneumonia; SC, sputum culture; ssUAD, serotype-specific urine antigen testing.

Figure 2

Characterisation of pCAP by age and year. Proportion by age represents pCAP cases identified by (A) any or (B) all diagnostic tests for Streptococcus pneumoniae, (C) incidence rates for pCAP for cases identified by any test and (D) incidence rates for pCAP for cases identified by all tests. pCAP, pneumococcal community-acquired pneumonia.

Figure 3

Contribution by age and year of pCAP attributed to PCV13 serotypes. Proportion of cap cases attributed to PCV13 serotypes in cap cases tested using (A) any or (B) all diagnostic tests for Streptococcus pneumoniae, (C) incidence rates for pCAP attributed to PCV13 serotypes for pCAP cases identified by any test and (D) incidence rates for pCAP for cases identified by all tests. pCAP, pneumococcal community-acquired pneumonia.

Figure 4

Streptococcus pneumoniae serotype distribution in adults hospitalised with pCAP. (A) Characterisation by age of S. pneumoniae serotypes identified in pCAP (n=418). Incidence rates for the predominant three serotypes are presented over time: (B) serotype 7F, (C) serotype 19A and (D) serotype 3. pCAP, pneumococcal community-acquired pneumonia.