Short-term mortality in relation to age and comorbidity in older adults with community-acquired bacteremia: A population-based cohort study

OBJECTIVES: To assess 30-day mortality from bacteremia in relation to age and comorbidity and the association between age and mortality with increasing comorbidity. DESIGN: Population-based cohort study. SETTING: North Jutland County, Denmark. PARTICIPANTS: Adults in medical wards with community-acquired bacteremia, 1995 to 2004. MEASUREMENTS: Smoothed mortality curves and computed mortality rate ratios (MRRs) using Cox regression analysis. RESULTS: Two thousand eight hundred fifty-one patients, 851 aged 15 to 64, 1,092 aged 65 to 79, and 909 aged 80 and older were included. Mortality increased linearly with age. Compared with patients younger than 65, adjusted MRRs in patients aged 65 to 79 and 80 and older were 1.5 (95% confidence interval (CI)=1.2-2.0) and 1.8 (95% CI=1.4-2.3), respectively. Mortality also increased with level of comorbidity. Compared with patients with low comorbidity, adjusted MRRs in patients with medium and high comorbidity were 1.5 (95% CI=1.2-1.8) and 1.7 (95% CI=1.4-2.2), respectively. Regardless of the level of comorbidity, MRRs were consistently higher in older than in younger patients. CONCLUSION: Older age and greater comorbidity predicted mortality, and increasing age-related comorbidity did not explain the effect of age.