Table 1.

Impact of Comorbidity on Clinical Care: Overview of Classification Systems

Kaplan et al12,34,35Diagnostic comorbidity“An associated disease [whose]…manifestations can simulate those of the index disease” (eg, pneumonia and pulmonary infarction)
Prognostic comorbidityDiseases “[in relation to an index disease] graded according to their anticipated effects on therapy and life expectancy [as]”
Cogent“Comorbid ailments expected to impair a patient’s long-term survival” (eg, recent severe stroke)
Noncogent“Other ailments” (eg, congestive heart failure or myocardial infarction more than 6 months old)
Angold et al16Homotypic comorbidity“Disorders within a diagnostic grouping” (eg, major depression and dysthymia)
Heteroptypic comorbidity“Disorders from different diagnostic groupings” (eg, major depression and conduct disorder)”
Piette and Kerr36Concordant comorbidity“[Diseases as] parts of the same pathophysiologic risk profile and more likely to share the same management and are more likely to be the focus of the same disease management plan” (eg, type 2 diabetes mellitus and hypertension)
Discordant comorbidityDiseases that are “not directly related in either pathogenesis or management and do not share an underlying predisposing factor” (eg, type 2 diabetes mellitus and irritable bowel syndrome)