Table 2.

Examples of the terms found in literature: their definitions and meanings

Terms used	Defined and used according to definition	Comorbid/multimorbid	Notes
Chronic medical conditions/comorbidities	Bayliss et al.20
Coexisting chronic conditions		Egede21	Not clear whether comorbid or multimorbid
Comorbidities		Van Weel and Schellevis22	Coexisting also used; uncertain if this is separate meaning to comorbid
		Verbrugge et al.23	In contrast with above this article defines comorbid as ‘several conditions simultaneously’
Comorbid chronic illnesses		Bayliss et al.24	Multiple chronic medical conditions used in title; uncertain if referring specifically to comorbid or more broadly to multimorbid illnesses
Complex chronic diseases	Sevick et al.25		Defined as multiple morbidities; signifies new direction of research identifying complex needs
Concurrent chronic illnesses		Williams and Botti26	Used as comorbid
Concurrent chronic conditions	Fortin et al.10		Includes concepts of comorbidity and multimorbidity
Concurrent medical conditions	Fortin et al.27		Includes the concepts of comorbidity and multimorbidity
Burden of chronic disease	Bodenheimer et al.28		Defined as having more than one chronic condition
Multiple chronic diseases		Walker29	Defined as comorbid
Multimorbidity	Van Den Akker9		Defined as co‐occurrence of two or more diseases in person without a defined index disease
	Smith and O'Dowd30		As above but examples in article might be seen as comorbidities
	Ritchie31		Simultaneous existence of more than 1 pathophysiologic condition
Multiple morbidity	Schoenberg et al.32
Multiple conditions	Fortin et al.11		Multimorbidity used in title; multiple chronic medical conditions used in article
Multiple coexisting medical conditions		Laux et al.33	Appears not to distinguish between comorbid or multimorbid because research based on episodes of care
Multiple chronic conditions		Higashi et al.34	Article discusses quality of care based on number of medical conditions without distinguishing whether comorbid or not.
Multiple chronic health conditions		Loeb et al.35	Multiple chronic conditions used in title, then, article combines this with multiple chronic health conditions
Multiple chronic illnesses	Parchman.36
Multiple chronic medical disorders		Piette et al.37	Multiple chronic illnesses used in title; multiple chronic medical disorders used in article; article discusses diabetes and comorbid depression; suggests the conceptual framework suitable to multiple chronic medical disorders
Unrelated disorders		Redelmeier et al.38	Title uses unrelated disorders. Article does not distinguish between comorbid or multimorbid; deals with treatments related to index disease