Mortality in the thirteen years following invasive pneumococcal disease

Background

Traditionally considered an acute disease, there is increasing evidence that Invasive Pneumococcal Disease (IPD) is associated with higher longer-term mortality than might be expected (Floeystad et al., 2017 May; Versluys et al., 2022 Aug; Versluys et al., 2022).

Aim

To investigate IPD mortality over a prolonged time period and identify predictors and causes of early versus later mortality.

Design

A previous retrospective cohort study was undertaken with 207 consecutive adult patients diagnosed with IPD at Hull University Teaching Hospitals NHS Trust, 2007–2009. The present study followed this cohort to 2023.

Methods

Clinical notes were reviewed and patient characteristics and causes of death recorded. United Kingdom life expectancy tables were used to calculate expected remaining years of life according to patient age and calculate the difference between the observed and expected life years, stratified by potential predictor variables to identify associations with loss of life-years. Piecewise multivariate Cox Proportional Hazards (CPH) models were constructed to identify statistically significant predictors for early, medium-term, and long-term mortality.

Results

21 % of patients died within 30 days, 39 % by 2 years, and 69 % by 13 years. Most early deaths, according to death certification, were due to infection, whereas later deaths were predominantly due to malignancy or infection. Compared to the Hull region, there were significantly more deaths from infection and malignancy, and fewer from cardiovascular disease. The total difference between observed and expected was 985 life years for the cohort. Age, Charlson score, and pyrexia on admission were significant predictors of late mortality.

Conclusions

Age and comorbidity burden are predictors of mortality after IPD with infection and malignancy being important causes of later mortality. Clinicians should be mindful of undiagnosed malignancies when managing IPD and consider reviewing the stability of existing comorbidities either prior to or shortly after discharge from hospital.