A quick review of case-mix modeling might be useful at this point. In case-mix models, the criterion variable is some measure of resource use, and assessment data comprise the independent variables. Assessment information and resource data are combined to create groups of care recipients who use relatively similar levels of care resources and share common characteristics.7
The dependent variable
The dependent variable in these analyses was Medicaid home care expenditures for one year following the assessment of a sample member. The expenditure data were obtained from the Texas Medicaid Program. All references to expenditures refer to US dollars. Other case-mix models have monetized and included an adjustment for informal care in the dependent variable.11 Data on informal care were not, unfortunately, included in this data collection.
Variables for potential inclusion in the classification model
Assessors completed the assessment with information from a variety of sources: client medical records, other Medicaid agency records, and responses from informal caregivers and, when possible, from the child or youth being assessed. These data included, but were not restricted to, information on medical diagnoses, health conditions, cognitive function, behaviors, continence, nursing needs, treatments and therapies, and the performance of ADLs.
An important aspect of the measurement strategy for the instruments came in measuring functional performance. All ADL items used six response codes that ranged from total independence to total dependence. The summary ADL scale used in these analyses, for purposes of some consistency with ADL scale in the RUG III Home Care (RUG-III/HC) model, summed the scores for only four ADLs11—eating, bed mobility, transfer, and toilet use (α = 0.83). A more lengthy discussion of the strategy used for functional measurement in the PEDS HC is available elsewhere.22,27
The measure of incontinence indicated whether a child or youth was always, or almost always, incontinent of bowel or bladder. The measure of cognitive issues focused on the child or youth’s ability to make independent decisions. The child or youth was considered to be receiving habilitative services if she or he was receiving physical or occupational therapy.
Many behaviors observed with children facing special health care challenges are troubling to observers or caregivers. However, only three of 17 indicators of problem behavior in the PEDS HC significantly affected annual expenditures: resisting assistance with personal care, resisting therapies or treatments, or harming oneself (nonsuicidal). The occurrence of any of these behaviors in seven days before the assessment was considered indicative of a behavior problem.
Using the RUG-III/HC model as a starting point
The availability of the RUG-III/HC case-mix model, which is widely used in adult home care, provided a strong foundation for the development of a pediatric classification model.10,11 The RUGIII/HC model includes the following seven general categories:
- special rehabilitation (based on the provision of therapies)
- extensive services (parenteral feeding, suctioning, or use of a ventilator/respirator)
- special care (the presence of intravenous medications, tube feeding, or multiple sclerosis)
- clinically complex (the presence of aphasia, cerebral palsy, pneumonia, or stasis ulcer)
- impaired cognition (largely based on memory, comprehension, and decision making)
- behavior problems (wandering, inappropriate behavior, abusive actions, or hallucinations)
- reduced physical function (functional impairment among those who qualify for no other category).
The RUG-III/HC system is hierarchical; a person may fit the first category (special rehabilitation). If they do, they are considered a member of that category; if not, then the researcher determines whether the person fits into the next category (extensive services). This process continues until the person is placed in a category or resides in the lowest category (reduced physical function). The P/ECM is also a hierarchical model, one that uses five of the seven RUG-III/HC categories. The RUG-III/HC category definitions were the starting point for the P/ECM category definitions.
The P/ECM category definitions were, however, also based on the analyses of a wide range of PEDS HC items. Bivariate analyses compared expenditures for those with a specific condition or impairment included in the PEDS HC to expenditures for those without the condition or impairment. The results of these analyses were used to modify the RUG-III/HC categories, making them more appropriate for a pediatric home care population.
The P/ECM also clearly deviates from the RUG-III/HC model in that it contains no special rehabilitation category. Among the adult home care populations, the special rehabilitation category is populated with a relatively small percentage of the older adults who are receiving assistance in recovering from an acute episode (eg, joint or limb replacement and stroke). That is not the case for children or youth. Therapies (rehabilitation or habilitation) are provided to a much larger and more diverse population of children receiving home care. Creating a special rehabilitation category in the P/ECM would have placed roughly half the study sample in the first major classification category.
Unlike the RUG-III/HC model, behavior problems were not included as a major category in the P/ECM. A measure of behavior problems was used, instead, to determine whether behaviors had a significant effect within each P/ECM group that emerged in the initial classification analysis. This analysis led to additional “splits” in preliminary groups in two P/ECM categories.