Understanding the High Prevalence of Low-Prevalence Chronic Disease Combinations: Databases and Methods for Research. Definitions of Multiple Chronic Conditions


One of the difficulties in studying multiple chronic conditions is the lack of a clear definition of the phenomenon. For example, the official definitions in Exhibit 3 below, created by three organizations, are similar but not the same. A recent paper by Goodman and colleagues provides a robust discussion of definitional issues related to multiple chronic conditions and elaborates the many different definitions being used in different contexts by different stakeholders (Goodman, et al., 2013). In addition, the authors offer a conceptual model for classifying chronic conditions and call for a collaborative process to begin to standardize and systemize definitions and set of conditions that are important for clinical practice, research and policy making.

Exhibit 3: Definitions of Multiple Chronic Conditions by Three Organizations

Organization Definition of Multiple Chronic Conditions
HHS Assistant Secretary for Health Chronic conditions are conditions that last a year or more and require ongoing medical attention and/or limit activities of daily living. They include both physical conditions such as arthritis, cancer, and HIV infection. Also included are mental and cognitive disorders, such as ongoing depression, substance addiction, and dementia. MCC are concurrent chronic conditions. In other words, multiple chronic conditions are two or more chronic conditions that affect a person at the same time. For example, either a person with arthritis and hypertension or a person with heart disease and depression, both have multiple chronic conditions (DHHS 2013).
National Quality Forum Two or more concurrent chronic conditions that collectively have an adverse effect on health status, function, or quality of life, and that require complex healthcare management, decision-making, or coordination (NQF 2012).
Institute for Medicine Definition: Long-term health conditions that threaten well-being and function in an episodic, continuous, or progressive way over many years of life (IOM 2012).

In a study of Medicare patients, Fortin and his colleagues (2012) concluded that the lack of uniformity in definition results in dramatically different prevalence estimates. Because there are numerous different constellations of MCC (particularly low prevalence MCC), researchers have used simple counts of the number of conditions an individual has as a measure of intensity or comparison. Although the specific conditions that are included differ by study, reporting only the number of MCC can lead to inconsistent conclusions and lack of comparability (Fortin et al. 2012 & Salive, 2013). Individuals with MCC are often defined as “complex patients,” which is both a physiological description that encompasses the complexity of having more than one condition as well as a characterization of their interface with the health care system—which is complicated by multiple conditions (Rich et al., 2012, Safford et al., 2007, & Grant et al., 2011).

Consensus-building efforts may in the future help to refine the definition of MCC used by researchers. In the meantime, given the sparse literature, we examined all papers related to multiple chronic conditions reagardless of the definition used by the authors.

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