The primary diagnosis is the main reason a patient entered the hospital for treatment and care. This is the diagnosis provided by the admitting doctor. In some cases, a pre-existing condition or one occurring when the patient was admitted, are categorized as CC(comorbid condition) or MCC (major comorbid condition).
Patients with MCC (major comorbidities) like acute congestive heart failure or sepsis will require more resources and care to treat the main diagnosis. A patient DRG with CC (not-so-major comorbid conditions) like an acute flare-up of chronic COPD do not require as many resources, but may spur complications during the stay while treating the main diagnosis.
ClaraPrice provides lists of conditions and complications that are included in the ICD-10 coding data provided by CMS, the government department watching medical billing and patient claims.