What PDGM changed
The Patient-Driven Groupings Model took effect January 1, 2020 and replaced the old Prospective Payment System. Two structural changes matter most: the unit of payment became a 30-day period instead of a 60-day episode, and reimbursement is now driven by patient characteristics rather than the number of therapy visits. Volume of therapy no longer increases payment — clinical and functional need does.
The five case-mix variables
Every 30-day period is sorted into one of 432 case-mix groups using five inputs:
| Variable | Options |
|---|---|
| Admission source | Community vs. Institutional (facility stay in the prior 14 days) |
| Timing | Early (first 30-day period) vs. Late (all subsequent) |
| Clinical grouping | One of 12 groups from the principal diagnosis |
| Functional level | Low / Medium / High — from OASIS-E functional items |
| Comorbidity adjustment | None / Low / High — from secondary diagnoses |
Where OASIS-E comes in
OASIS-E (effective January 1, 2023) is the assessment completed at start of care, recert, resumption, transfer, and discharge. Its functional items — grooming, dressing, bathing, toilet and bed transferring, ambulation, and risk of hospitalization — are scored into the points that set the low / medium / high functional level in PDGM. The same data feeds your publicly reported quality measures, so an OASIS error is both a payment problem and a star-rating problem.
The denials that hurt most
Under PDGM the costliest mistakes are administrative, not clinical. A late Notice of Admission(due within five calendar days of start of care) forfeits payment for every day it's late. A principal diagnosis that doesn't map to a valid PDGM clinical group becomes a questionable encounter and returns the claim. Missing or invalid OASIS submission to iQIES, face-to-face documentation gaps, and order or signature timing issues round out the list. Every one of these is catchable before the claim goes out.
How a modern EMR prevents the leakage
This is the case for validation-first software: OASIS data-quality checks before export, automatic PDGM grouping so billing sees the projected reimbursement up front, NOA timers, diagnosis mapping that flags questionable encounters at the point of coding, and billing holds that won't release a claim with a known defect. That's exactly how the Copergrine Home Health & Therapy EMR is built — OASIS-E validation gates, PDGM grouping, EVV, AI-drafted 485s, and a billing-holds engine that prevents silent denials.