Initial home health outcomes under prospective payment

Health Services Research, Feb, 2005 by Robert E. Schlenker, Martha C. Powell, Glenn K. Goodrich

The three utilization outcomes of acute care hospitalization, discharge to the community, and emergent care serve as additional proxy measures of patient health status changes. The hospitalization and discharge rates (percentages) typically account for over 95 percent of all episodes. Admissions to nursing and rehabilitation facilities and patients moving to other geographic areas account for most of the rest. Patients who die while receiving home health care are excluded from the outcome measures in the CMS reporting system.

The variables used as patient risk factors in the outcome models also are derived from OASIS data for the SOC. Most of the OASIS items are used in one or more risk models to derive predicted outcome rates for the CMS outcome reports. For each outcome, 20-40 risk factors are typically included in CMS models to estimate predicted outcome rates. Risk factors include patient demographics, functional status, prognoses, and diagnoses. Table 1 lists the 37 risk factors included in the CMS risk model for improvement in ambulation/locomotion. All estimated risk models can be found at the website noted in the table. In general, the models are similar to the example in Table 1 in terms of the number and type of risk factors.

Visit Measures and HHRGs

Medicare claims data provide information on visits by discipline and date of service for the six Medicare-covered home health disciplines of skilled nursing, physical therapy, occupational therapy, speech/language pathology, medical social services, and aide services. We used four measures of visits per episode: total, skilled nursing, therapy, and aide. The therapy measure combines physical therapy, occupational therapy, and speech/language pathology visits. We excluded medical social services from the discipline-specific measures because they represent a small proportion of total visits. (They are, however, included in total visits.)

We used the PPS HHRGs to control for patient case mix in the visit analyses. Although the OASIS was created primarily for outcome measurement and risk adjustment, a subset of OASIS items also is used to define the HHRGs to adjust PPS payment for case mix (Goldberg et al. 1999; HCFA 1999b, 2000). Each HHRG is comprised of three domains or dimensions--clinical, functional, and service. Each dimension has several levels; point scores are associated with specific OASIS item responses, and the points are summed to determine the patient's level for the dimension.

The clinical dimension is based on factors including selected diagnoses, sensory impairments, dyspnea, pressure ulcers, incontinence, and behavioral problems. The functional domain is based on six activities of daily living (ADLs)--dressing upper/lower body (two ADLs), bathing, toileting, transferring, and ambulation/locomotion. The service dimension is not based directly on patient characteristics but on (a) the patient's institutional setting in the 2-week period prior to start of the home health episode (i.e., hospital, rehabilitation facility, or skilled nursing facility) and (b) the amount of therapy received (physical, occupational, or speech/language pathology) during the 60-day home health PPS payment episode. A patient receiving 10 or more therapy visits during a payment episode is categorized into a high-therapy HHRG. The service measures are intended as proxy indicators of patient case mix and need for services.