What PDGM Changed and Why It Matters
The Patient-Driven Groupings Model replaced the previous Prospective Payment System (PPS) in January 2020, fundamentally restructuring how Medicare reimburses home health agencies. Under the old model, therapy visit thresholds drove payment. Under PDGM, clinical characteristics, functional impairment, and comorbid conditions determine reimbursement.
This shift had profound implications. Agencies that had built therapy-heavy care models suddenly faced reimbursement structures that rewarded accurate clinical documentation and diagnosis coding over visit volume. The agencies that adapted quickly—those with strong coding operations—thrived. Those that didn’t saw margins compress significantly.
The Five Elements That Determine Your PDGM Payment
Every 30-day payment period under PDGM is classified across five dimensions: admission source (community vs. institutional), timing (early vs. late), clinical grouping (one of twelve functional and clinical categories), functional impairment level (low, medium, or high), and comorbidity adjustment (none, low, or high).
The combination of these five elements produces a case-mix weight that, multiplied by the base payment rate, determines your agency’s reimbursement. A high-complexity patient appropriately coded and documented can generate significantly more revenue than the same patient with incomplete or inaccurate documentation.
Where Agencies Leave Money on the Table
The most common revenue leakage under PDGM occurs at the diagnosis coding level. The primary diagnosis determines which of the twelve clinical groupings a patient falls into, and groupings carry dramatically different payment weights. Musculoskeletal rehabilitation groupings, for example, pay at rates 20–40% lower than neuro-rehabilitation or wound care groupings.
When coders select a musculoskeletal code as primary when the clinical record actually supports a higher-paying neurological or wound care grouping, agencies lose revenue they legitimately earned. This is not about upcoding—it’s about ensuring that the coded claim accurately reflects the clinical complexity documented in the record.
Functional Scoring and Its Revenue Impact
The functional impairment level within PDGM is determined by four OASIS items: M1800 (grooming), M1810 (dressing upper body), M1820 (dressing lower body), and M1830 (bathing). These four items, combined, create the functional score that determines whether a patient classifies as low, medium, or high impairment.
A patient classified as high functional impairment generates substantially more revenue than the same patient classified as low. Accurate OASIS scoring—neither overcoding nor undercoding functional limitations—is therefore critical to appropriate reimbursement. AI-assisted OASIS review catches the scoring inconsistencies that manual review routinely misses.
Optimizing Your PDGM Performance
The agencies with the strongest PDGM performance share three characteristics: robust coding operations with certified specialists, systematic OASIS review processes, and real-time visibility into their case-mix composition. They monitor their average case-mix weight monthly and investigate when it deviates from expected ranges.
Achieving and sustaining strong PDGM performance requires treating revenue cycle management as a clinical operations function, not an administrative one. The documentation decisions clinicians make on every patient visit directly determine reimbursement—and the agencies that help their clinical teams understand this connection are the ones outperforming their peers.