Adjusted clinical group system: studies
The adjusted clinical group system, a population/patient case-mix adjustment system based on medical records or insurance claims,measures health status by grouping diagnoses into clinical cogent groups. The ACG system was originally designed assessment of severity or disability. These measures,however,are often base on a more restricted list of disease than measures based on records.
There are limitations to measures that use complex scoring. Changes to disease coding system may mean the weight need to be reestimateed ,and relevant drugs use in medication-based measures are constantly changing,so scoring algorithm need regular updating. Proprietary risk adjustment systems,such as the ACG System, tent to use scoring systems that are not transparent and often have considerable costs to end-users.
The most common approach to measuring multi morbidity is disease counts. Even so, it is to compare finding between studies, are different authors included very different numbers of diseases, sometimes providing no details about with diseases are included or the criteria for inclusion. Most studies are based counting so-called chronic diseases,but chronicity is rarely defined. The number of diseases is also related to the level of diseases abstraction-for example,some measures counts cancer as one condition, whereas others count each malignancy separately.
It might be anticipated that such measures as the Charlson index, the ACG system,and the DUSOI , which weight different conditions, would be more effective at predicting outcome than simple counts, which weight all conditions equally. Some studies, however, have concluded that simple measures, such as a simple count of chronic diseases or of prescribed medications, are almost as effective at predicting mortality and health care utilization as more sophisticated methods and may be much simpler to use despite the reservation outlined above.
Part of the problem in choosing an appropriate measure is due to the abstract nature of concept of multi morbidity and how it relates to other concepts, such as diseases burden and patient complexity. It is important the measures are based on an underlying conceptualization of why and how multi morbidity is expected to have an impact on other variables. For example, the impact of multi morbidity on quality of life is likely to be most appropriately assessed using a self-report measures that takes account of the functional ability, whereas the impact on health care utilization is likely to be best assessed using a measures that was derived using empirical weights to predict this outcome.
Relatively few studies have directly compared the performance of different measures in a primary care context , and the finding do not show the clear superiority of the measures over another. Evidence about the reliability of these measures when use in a primary care or population setting is also limited. Evidence about the reliability of measures when used in hospitalized patients and specialist secondary care settings may not necessarily pertain to primary care settings, where patients characteristics, disease classification, record system, and staffing are very different.