Validity of the Modified Charlson Comorbidity Index as Predictor of Short-term Outcome in Older Stroke Patients

The modified Charlson Comorbidity Index (MCCI) has been proposed as a tool for adjusting the outcomes of stroke for comorbidity, but its validity in such a context has been evaluated in only a few studies and needs to be further explored, especially in elderly patients. We aimed to retrospectively assess the validity of the MCCI as a predictor of the short-term outcomes in a cohort of 297 patients with first-ever ischemic stroke, older than 60 years, and managed according to a clinical pathway. The poor outcome (PO) at 1 month, defined as a modified Rankin Scale score of 3-6, was the primary end point. Furthermore, a new comorbidity index has been developed, specific to our cohort, according to the same statistical approach used for the original CCI. The MCCI showed a positive association with PO (odds ratio [OR] 1.62; 95% confidence interval [CI] .98-2.68) and mortality (hazard ratio [HR] 1.85; 95% CI .94-3.61), not statistically significant and totally dependent on its association with the severity of neurologic impairment at onset. The new comorbidity index showed, as expected, a significant association with the PO and mortality with higher point estimates of OR (2.74; 95% CI 1.64-4.59) and HR (2.73; 95% CI 1.51-4.94), but this association was also dependent on stroke severity and premorbid disability. Our results do not support the validity of the MCCI as a predictor of the short-term outcomes in elderly stroke patients nor could we develop a more valid index from the available data. This suggests the need for development of disease- and age-specific indexes, possibly according to a prospective design. In any case, initial stroke severity, a strong predictor of outcome, is associated with the degree of comorbidity.