Subacute and non-acute casemix in Australia

Synopsis

• The costs of subacute care (palliative care, rehabilitation medicine, psychogeriatrics, and geriatric evaluation and management) and non-acute care (nursing home, convalescent and planned respite care) are not adequately described by existing casemix classifications.
  
• The predominant treatment goals in subacute care are enhancement of quality of life and/or improvement in functional status and, in non-acute care, maintenance of current health and functional status.
  
• A national classification system for this area has now been developed -- the Australian National Sub-Acute and Non-Acute Patient Classification System (AN-SNAP).
  
• The AN-SNAP system, based on analysis of over 30 000 episodes of care, defines four case types of subacute care (palliative care, rehabilitation, psychogeriatric care, and geriatric evaluation and management) and one case type of non-acute care (maintenance care), and classifies both overnight and ambulatory care.
  
• The AN-SNAP system reflects the goal of management -- a change in functional status or improvement in quality of life -- rather than the patient's diagnosis. It will complement the existing AN-DRG classification.

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Introduction The Australian healthcare system is about to implement a new casemix classification system for subacute and non-acute care, the costs of which are not adequately described by traditional diagnostic tools. Subacute care comprises palliative care, rehabilitation medicine, psychogeriatrics, and geriatric evaluation and management. Non-acute care includes nursing home, convalescent and planned respite care. The new casemix classification system, which includes hospital as well as community care, reflects the goal of management -- a change in functional status or improvement in quality of life -- rather than the underlying patient diagnosis.

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Background Subacute casemix has been evolving for 15 years. In 1983, when the United States Health Care Financing Administration decided that payments for hospital care would be on a prospective payment system, based on acute-care diagnosis-related groups (DRGs), rehabilitation, psychiatric, children's and long-term facilities were specifically excluded. It was recognised that these forms of care, although not acute, were still complex and expensive and required long hospital stays.

In 1987, a US Department of Health and Social Services report reiterated that their current DRG system did not adequately take into account the special circumstances of patients requiring long hospital stays.¹ Studies in the United States over the following few years not only confirmed that DRGs did not adequately describe costs in one of these areas of care (rehabilitation medicine),² but that as a consequence quality of care had deteriorated, as measured by changed length of hospital stay, increased readmission rates and a rising number of nursing home admissions.^3-5

As casemix development progressed in Australia, Australian studies^6-12 also expressed the need for a different approach for costing of rehabilitation,^6,8-10,12 geriatric evaluation and management,^6,9,12 palliative care^7,9,11,12 and psychogeriatrics.^6,12

The term subacute care was coined in 1992¹³ to describe "care which is provided for a person who requires health services but whose principal medical diagnosis (modified for factors such as age and procedures) is not adequate in explaining the need for, or the cost of, the services that s/he receives".

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Goals of subacute and non-acute care In subacute care the predominant goal is enhancement of a patient's quality of life and/or improvement in his or her functional status. In non-acute care the predominant goal is maintenance of a patient's current health and functional status. Because of this difference in goals, it was expected that factors other than diagnosis were more likely to explain the costs of these forms of care.

Rehabilitation: Factors contributing to the success of rehabilitation programs have included patient characteristics such as functional status on admission, age, disease site, time from referral to beginning of program, comorbidities such as cognitive function and depression, and availability of resources.^14-16 The factor which appears in US and Australian studies to predict cost most accurately in these areas of care is a patient's functional status on admission.^12,15-17

Palliative care: Australian clinicians were instrumental in developing a casemix classification system with a primary approach from a clinical perspective. The development involved broad consultation and collaboration. The palliative care classification identified stage of illness or palliative care phase (eg, stable, deteriorating, terminal), symptom severity and acuity level (or nursing dependency) as the major factors explaining costs for this form of care.⁷

Psychogeriatrics and other aged care: The goals of admission in aged care are improving health status, modifying symptoms and enhancing function, living conditions, behaviour and quality of life.¹²

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Subacute and non-acute care classifications Several classification systems for subacute and non-acute episodes of care have been developed, including the Resource Utilisation Groups and the California Long Term Care System.¹⁸ The Resident Classification Index¹⁹ is an Australian classification system used in nursing homes to classify non-acute episodes of care. In the United States the FIM-FRG system (Functional Independence Measure- Function Related Groups)¹⁷ for rehabilitation medicine is the most developed.

Studies in Australia have continued to demonstrate that the best predictor of cost for subacute care is the goal of care. The most recent studies are the 1995 Victorian Rehabilitation Casemix Report¹⁰ and the 1996 NSW Sub-Acute Casemix Area Network Project.¹²

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AN-SNAP study The Australian National Sub-Acute and Non-Acute Patient Casemix Study²⁰ was conducted in 1996 in 99 hospital and community health sites in all Australian States and Territories and in five sites in New Zealand. Over 30 000 episodes of care were analysed, including overnight, same day, outpatient and community episodes of care.

The study established that there are five case types of subacute and non-acute care. Subacute care includes palliative care, rehabilitation, psychogeriatric care, and geriatric evaluation and management; and the final case type -- maintenance care -- is defined as non-acute care. Each of the five case types is defined according to the characteristics of the patient and the goal of care, and not the institution or service in which she or he is treated (eg, a patient may receive geriatric evaluation and management in a hospice, or palliative care in a rehabilitation unit).

A critical finding of the study was that across the spectrum of case types and classes there is significant diversity in the cost of subacute and non-acute care for both overnight and ambulatory episodes. For example, there is a 30-fold variation in episode cost and a five-fold variation in per diem cost between the most expensive and the least expensive classes in the overnight classification, thus confirming the necessity for a classification in this area to allow for appropriate output-based funding.

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AN-SNAP classification system From the study, a national classification for subacute and non-acute care was developed -- the Australian National Sub-Acute and Non-Acute Patient Casemix Classification System, or AN-SNAP classification.²⁰

AN-SNAP version 1 (Box 1)²¹ classifies both overnight and ambulatory care. It has 134 classes and the classification explains 58% of the variation in all episode costs. Of this 58%, 21% is contributed by episode type and 37% by the classes. The overnight branch has 66 classes and the classification explains 47% of the variance in the cost of overnight care. The ambulatory branch has 68 classes and the classification explains 28% of the variance in the cost of ambulatory care. These results are an improvement on the performance achieved by acute-care DRGs.

Analysis of the decision trees for overnight and ambulatory care in Box 1 shows the factors which have been incorporated into the system as predictors of cost.

• Palliative care -- phase, functional dependence as measured by RUG-ADL (resource utilisation groups - activities of daily living),¹⁸ and age;

• Rehabilitation -- impairment groupings, functional status as measured by FIM (Functional Independence Measure),²² and age;

• Psychogeriatrics -- psychiatric symptom severity and functional status as measured by the HoNOS (Health of the Nation Outcome Scale);²³

• Geriatric evaluation and management -- cognitive status in addition to motor capacity and age; and

• Maintenance care -- functional status.

The AN-SNAP study showed that the variables driving costs in the inpatient setting are also important cost drivers in the ambulatory setting. However, community care is inherently more complex than institutional care. Common variables across institutional and community care are necessary, but are insufficient in explaining cost variations. In consequence, the classification makes use of some community variables not required in institution care (eg, provider type and assessment or treatment episode).

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Implications of AN-SNAP The implementation of this classification has important implications. Firstly, a number of classifications are now available in Australia and policy decisions on the interaction between these classifications are required. Secondly, data on many of the characteristics used in AN-SNAP are currently collected by individual service providers, but most are not routinely collected by existing hospital and community information systems.

AN-SNAP, along with its further development, has been endorsed by the Australian Casemix Clinical Committee for adoption as the national classification for sub- and non-acute care. Implementation remains a State and Territory issue which requires a planned, staged approach.

Already some States, including Queensland and New South Wales, are implementing AN-SNAP, and others have indicated their intention to do so in the near future. The adoption of the system will complement the existing DRG system, as illustrated in the New South Wales approach (Box 2).

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References

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19. Commonwealth Department of Health, Housing and Community Services. Classification of nursing home residents. Handbook for directors of nursing. Canberra: DHHCS, 1992.
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Authors' details South Eastern Sydney Area Health Service, Sydney, NSW.
Lynette A Lee, FAFRM, FRACMA, Director Clinical Services.

Centre for Health Service Development, University of Wollongong, Wollongong, NSW.
Kathy M Eagar, MA(Psych), Associate Professor and Director.

Neringah Palliative Care Service, Sydney, NSW.
Michael C Smith, MB BS, MRACMA, Director.

Reprints will not be available from the authors.
Correspondence: Dr L A Lee, South Eastern Sydney Area Health Service, PO Box 430, Kogarah, NSW 1485.
E-mail: leelATsesahs.nsw.gov.au