List two patient level factors that allow inpatient psychiatric facilities to receive per diem payments

Any two of the following:
the patient's age (increasingly higher rates for patients age 45 and older through age 80 and above)

variable per diem adjustments (higher per diem payments for the first days of the patient's stay, gradually decreasing through the 22nd day of hospitalization, with no further decrease beyond that point)

the Medicare Severity diagnosis related group (MS-DRG) for the stay

certain comorbidities. (Only one comorbidity adjustment is made for each comorbidity category, but adjustments for more than one comorbidity category are possible.)?