Are comorbidity indices useful in predicting all-cause mortality in Type 2 diabetic patients? Comparison between Charlson index and disease count.

BACKGROUND AND AIMS: Several studies have shown that comorbidity is important in predicting morbidity and mortality in the general population. However, few studies have assessed the validity of comorbidity indices in diabetic patients. The aim of the present study was to compare the predictive value of disease count and Charlson's Comorbidity Index (CCI) for 3-year mortality in type 2 diabetic (T2D) patients.
METHODS: The study was performed on a consecutive series of 1667 T2D outpatients. Comorbidity was assessed using Charlson's index, whereas the diseases used to calculate Charlson's score were taken into account for disease count. Information on all-cause mortality over the 3-year follow-up period was obtained from the City of Florence Registry Office.
RESULTS: Mean duration of follow-up (+/-SD) was 31.4+/-10.6 months. One hundred and ninety-nine (11.9%) patients died during follow-up, with a yearly mortality rate of 4.7%. At multivariate analysis, after adjustment for sex and age, each additional disease was associated with a 54 [37-77]% increase in all-cause mortality. Mortality increased by 31 [21-41]% for each incremental point of Charlson's comorbidity score.
CONCLUSIONS: A simple disease count is as predictive of mortality in T2D patients as the more complex Charlson's index. The possible usefulness of specific comorbidity indices in predicting incident disability in diabetic subjects needs to be further investigated.