Per-Diem to Case Rate

Convert daily rates to case-level using CMS geometric mean length of stay (GLOS).

Walkthrough

Per-diem rate for MS-DRG 470 (Knee Replacement)

Input: Hospital reports a per-diem rate of \$2,500/day for MS-DRG 470.

GLOS lookup: CMS MS-DRG weights table says DRG 470 has GLOS = 2.4 days.

Transform: Per-diem rates are not multiplied by GLOS. They are carried through as-is. GLOS is attached as a reference column and used during accuracy scoring.

Comparison at scoring time: When evaluating this rate against a case rate of \$6,000, scoring compares \$2,500 (per diem) vs \$6,000 / 2.4 = \$2,500 (case rate normalized to per-diem). They agree — both rates are supported.

Per-diem rates are kept in native form but evaluated against case_rate / GLOS during accuracy scoring. This avoids compounding errors that would arise from multiplying rate × GLOS.

APR-DRG GLOS

For APR-DRG codes, the GLOS used is the average of the mapped MS-DRG GLOS values from the crosswalk table — one MS-DRG may map from multiple APR-DRG severity levels.