Effect of Age on the Manifestations and Outcomes of Invasive Pneumococcal Disease in Adults

Abstract

Background: Although a considerable amount is known about the effect of age on the manifestations and outcomes of pneumonia, the same is not true for invasive pneumococcal disease.

Methods: This was a prospective observational study of all cases (2435) of invasive pneumococcal disease in adults in Northern Alberta from 2000 to 2014. Rates of invasive pneumococcal disease per 100,000, sociodemographic variables, clinical characteristics, and invasive pneumococcal disease-related outcomes were compared for the following age groups: 17-54, 55-64, 65-74, and ≥75 years.

Results: The rate of invasive pneumococcal disease per 100,000 increased with increasing age. Although only 27.3% of the cases were in those aged ≥65 years, they accounted for 48% of the deaths. The case fatality rate increased with increasing age, from 9.6% for those aged 17-54 years to 31.7% for those aged ≥75 years. The rate of meningitis decreased with increasing age, as did admission to intensive care and use of mechanical ventilation. There was a marked reduction in the rate of invasive pneumococcal disease due to protein conjugate vaccine 7 and protein conjugate vaccine 13 serotypes in those aged ≥55 years but a much smaller decline in rates for those aged 17-54 years. Replacement with non-vaccine serotypes constituted approximately 50% of the cases.

Conclusions: The rate of invasive pneumococcal disease is highest in the very elderly, and manifestations of invasive pneumococcal disease are influenced by age.

Keywords: Age group; Invasive pneumococcal disease; Streptococcus pneumoniae.