The CCW includes variables for common chronic conditions and other chronic or potentially disabling conditions, which identify additional chronic health, mental health, and substance abuse conditions. These variables assist researchers in the identification of cohorts of beneficiaries with specific conditions. Researchers may request data for a specific predefined cohort based on any of the categories.

The CCW team develops the condition variables algorithms that search the CMS administrative claims data for specific diagnosis codes, MS-DRG codes, or procedure codes. The CCW algorithm specifications may change slightly from year to year due to changing claims coding standards. A "Change History" table is within the documentation for each group of conditions to assist CCW data users in identifying changes in the algorithms.

On October 1, 2015, the conversion from the 9th version of the International Classification of Diseases to version 10 (ICD-10) occurred. Regardless of the submission date of a claim for payment, services that occurred prior to October 1, 2015, use ICD-9 codes.

Algorithms are available for: