Functional Impairment Level

The functional impairment level is scored from a defined set of OASIS items covering self-care, mobility, and risk:

• M1800 Grooming
• M1810 and M1820 Ability to dress upper and lower body
• M1830 Bathing
• M1840 Toilet transferring
• M1850 Transferring
• M1860 Ambulation and locomotion
• M1033 Risk for hospitalization

Each response maps to points, the points are summed, and the total places the period into low, medium, or high impairment. Note that the GG items, while central to quality measures, are not what drives the PDGM functional level.

The point thresholds that separate low, medium, and high are not universal: they vary by clinical grouping, because functional limitation predicts resource use differently for a wound patient than for a neuro rehab patient. CMS recalibrates the response point values and thresholds annually, most recently in the CY2026 final rule using CY2024 data. The practical consequence is that identical OASIS answers can land in different functional levels depending on the clinical group, and a patient who scored medium last year might score differently this year under recalibrated thresholds with no change in condition.

Functional items are among the most consequential and most inconsistently answered items on OASIS. Understating impairment leaves payment on the table and can misrepresent the patient in quality measures. Overstating it inflates payment the documentation will not support, which is exactly what Additional Documentation Requests and program integrity reviews look for, and it also sets an artificially low baseline that makes later improvement measures look better than reality. The standard is observed ability on the day of assessment, considering safety, not best-case capability and not what the patient reports they used to do.

Agencies with reliable functional scoring share a few habits. Clinicians assess function by observing tasks rather than interviewing about them, and they document what they saw so the score is defensible. QA review compares OASIS functional responses against the visit narrative, therapy evaluations, and plan of care for consistency, because a patient scored as maximally dependent with a once-weekly nursing plan raises questions. Teams also track functional level distribution across clinicians: an assessor whose patients are consistently one level higher or lower than peers on similar caseloads is a calibration conversation, not a coincidence.