Disease Trends and Mortality From Invasive Pneumococcal Disease: A Long-Term Population-Based Study

Area of Science:

• Infectious Diseases
• Epidemiology
• Public Health

Background:

• Streptococcus pneumoniae causes significant invasive pneumococcal disease (IPD) and mortality globally.
• Pneumococcal conjugate vaccines (PCV) have reduced IPD incidence in many regions.
• Long-term mortality trends in IPD survivors are not well-documented.

Purpose of the Study:

• To analyze long-term mortality trends among IPD survivors in Iceland.
• To compare all-cause mortality rates between IPD patients and the general population.
• To assess the impact of PCV introduction on IPD mortality.

Main Methods:

• Analysis of all IPD cases in Iceland (1975-2020) with positive blood/CSF cultures.
• Assessment of 30-day and 5-year mortality rates across three decades (1985-2014).
• Comparison of age-standardized all-cause mortality rates (ASRs) between IPD patients and the general population.

Main Results:

• IPD incidence peaked in 1995-2004 and declined significantly post-2011 (p<.001).
• No significant improvement in 30-day mortality was observed over time (p=.98).
• IPD survivors had a 2.6-fold higher ASR for all-cause mortality compared to the general population (0.021 vs. 0.008 per person-year).

Conclusions:

• Despite declining IPD incidence, short-term mortality has not improved.
• A modest, non-significant improvement in 5-year mortality suggests potential benefits from chronic disease management.
• IPD survivors experience substantially elevated long-term mortality, necessitating focused interventions to reduce both acute and long-term risks.