Comorbidities present at the time of diagnosis were collected using the Adult Comorbidity Evaluation-27 index (ACE-27).  ACE-27 is a validated comorbidity instrument that provides a score (0–3) based on the number and severity of medical comorbidities.
ACE-27 resources:
Comorbidity collection form
ACE-27 online calculator
The Whole Picture: Coding Comorbidity Video