Charlson comorbidity score is a strong predictor of mortality in hemodialysis patients

Abstract

The Charlson comorbidity index (CCI) is a commonly used scale for assessing morbidity, but its role in assessing mortality in hemodialysis patients is not clear. Age, a component of CCI, is a strong risk factor for morbidity and mortality in chronic diseases and correlates with comorbidities. We hypothesized that the Charlson comorbidity index without age is a strong predictor of mortality in hemodialysis patients. A 6-year cohort of 893 hemodialysis patients was examined for an association between a modified CCI (without age and kidney disease) (mCCI) and mortality. Patients were 53±15 years old (mean±SD), had a median mCCI score of 2, and included 47% women, 31% African Americans and 55% diabetics. After adjusting for case-mix and nutritional and inflammatory markers including C-reactive protein and interleukin-6, 2nd (mCCI: 1-2), 3rd (mCCI=3), and 4th (mCCI: 4-9) quartiles compared to 1st (mCCI=0) quartiles showed death hazard ratios (95% confidence intervals) of 1.43 (0.92-2.23), 1.70 (1.06-2.72), and 2.33 (1.43-3.78), respectively. The mCCI-death association was robust in non-African Americans. The CCI-death association linearity was verified in cubic splines. Each 1 unit higher mCCI score was associated with a death hazard ratio of 1.16 (1.07-1.27). CCI independent of age is a robust and linear predictor of mortality in hemodialysis patients, in particular in non-African Americans.