Charlson Comorbidity Index

In this chapter, we consider the Charlson Comorbidity Index (CCI). This index is published, and the weights used to define risk adjustment in the logistic regression model are clearly identified as well. (Sundararajan et al., 2004) Therefore, we are able to examine this index in detail, and to see if the index is meaningful in terms of adjusting risk based upon patient condition. We will suggest an alternative to the Charlson Index in Chapter 8 that gives improvements in terms of its relationship to outcomes. In Chapters 6 and 7, we will discuss other commonly used severity index measures. We will compare their results to those computed using the Charlson Index. We will also continue to discuss the examples given in Chapter 4 of patients having cardiovascular bypass surgery and COPD (chronic obstructive pulmonary disease) in addition to other examples introduced in this chapter. Since the Charlson Index is published, it is not used by payers to rank the quality of providers. If it were used, the providers could focus on this minimal set of patient conditions. There is, of course, a similar danger if the developers of proprietary indices released, or sold, their model to healthcare providers who could use the values to focus on specific diagnosis codes. Therefore, in order to reduce the problem of upcoding, providers should not know the details of the model used.