Objectives: A patient's baseline health status may affect the ability to survive an acute illness. Emergency medicine research requires tools to adjust for confounders such as comorbid illnesses. The Charlson Comorbidity Index has been validated in many settings but not extensively in the emergency department (ED). The purpose of this study was to examine the utility of the Charlson Index as a predictor of one-year mortality in a population of ED patients with suspected infection.
Methods: The comorbid illness components of the Charlson Index were prospectively abstracted from the medical records of adult (age older than 18 years) ED patients at risk for infection (indicated by the clinical decision to obtain a blood culture) and weighted. Charlson scores were grouped into four previously established indices: 0 points (none), 1–2 points (low), 3–4 points (moderate), and ≥5 points (high). The primary outcome was one-year mortality assessed using the National Death Index and medical records. Cox proportional-hazards ratios were calculated, adjusting for age, gender, and markers of 28-day in-hospital mortality.
Results: Between February 1, 2000, and February 1, 2001, 3,102 unique patients (96% of eligible patients) were enrolled at an urban teaching hospital. Overall one-year mortality was 22% (667/3,102). Mortality rates increased with increasing Charlson scores: none, 7% (95% confidence interval [CI] = 5.4% to 8.5%); low, 22% (95% CI = 19% to 24%); moderate, 31% (95% CI = 27% to 35%); and high, 40% (95% CI = 36% to 44%). Controlling for age, gender, and factors associated with 28-day mortality, and using the “none” group as a reference group, the Charlson Index predicted mortality as follows: low, odds ratio of 2.0; moderate, odds ratio of 2.5; and high, odds ratio of 4.7.
Conclusions: This study suggests that the Charlson Index predicts one-year mortality among ED patients with suspected infection.