42 CFR § 412.620 - Patient classification system.

---
identifier: "/us/cfr/t42/s412.620"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "42 CFR § 412.620 - Patient classification system."
title_number: 42
title_name: "Public Health"
section_number: "412.620"
section_name: "Patient classification system."
chapter_name: "CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "B"
subchapter_name: "MEDICARE PROGRAM"
part_number: "412"
part_name: "PROSPECTIVE PAYMENT SYSTEMS FOR INPATIENT HOSPITAL SERVICES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 1302 and 1395hh."
regulatory_source: "50 FR 12741, Mar. 29, 1985, unless otherwise noted."
cfr_part: "412"
---


# 412.620 Patient classification system.

(a) *Classification methodology.* (1) A patient classification system is used to classify patients in inpatient rehabilitation facilities into mutually exclusive case-mix groups.

(2) For purposes of this subpart, case-mix groups are classes of Medicare patient discharges by functional-related groups that are based on a patient's impairment, age, comorbidities, functional capabilities, and other factors that may improve the ability of the functional-related groups to estimate variations in resource use.

(3) Data from admission assessments under § 412.610(c)(1) are used to classify a Medicare patient into an appropriate case-mix group.

(4) Data from the discharge assessment under § 412.610(c)(2) are used to determine the weighting factors under paragraph (b)(4) of this section.

(b) *Weighting factors*—(1) *General.* An appropriate weight is assigned to each case-mix group that measures the relative difference in facility resource intensity among the various case-mix groups.

(2) *Short-stay outliers.* We will determine a weighting factor or factors for patients that are discharged and not transferred (as defined in § 412.602) within a number of days from admission as specified by us.

(3) *Patients who expire.* We will determine a weighting factor or factors for patients who expire within a number of days from admission as specified by us.

(4) *Comorbidities.* We will determine a weighting factor or factors to account for the presence of a comorbidity, as defined in § 412.602, that is relevant to resource use in the classification system.

(c) *Revision of case-mix group classifications and weighting factors.* We may periodically adjust the case-mix groups and weighting factors to reflect changes in—

(1) Treatment patterns;

(2) Technology;

(3) Number of discharges; and

(4) Other factors affecting the relative use of resources.