Final answer:
MS-DRG 456 includes secondary conditions with a moderate severity of illness.
Step-by-step explanation:
The MS-DRG that includes secondary conditions with a moderate severity of illness is MS-DRG 456. This DRG is part of the Medicare Severity Diagnosis Related Group system, used to determine payment for hospital inpatient services. It groups together patients with similar clinical and resource utilization characteristics. MS-DRG 456 specifically includes cases with secondary diagnoses that have a moderate severity level.