title: A Systematic Review of Conceptual Frameworks of Medical Complexity and New Model Development.
abstract: BACKGROUND
  Patient complexity is often operationalized by counting multiple chronic conditions (MCC) without considering contextual factors that can affect patient risk for adverse outcomes.
  
  
  OBJECTIVE
  Our objective was to develop a conceptual model of complexity addressing gaps identified in a review of published conceptual models.
  
  
  METHODS
  We searched for English-language MEDLINE papers published between 1 January 2004 and 16 January 2014. Two reviewers independently evaluated abstracts and all authors contributed to the development of the conceptual model in an iterative process.
  
  
  RESULTS
  From 1606 identified abstracts, six conceptual models were selected. One additional model was identified through reference review. Each model had strengths, but several constructs were not fully considered: 1) contextual factors; 2) dynamics of complexity; 3) patients' preferences; 4) acute health shocks; and 5) resilience. Our Cycle of Complexity model illustrates relationships between acute shocks and medical events, healthcare access and utilization, workload and capacity, and patient preferences in the context of interpersonal, organizational, and community factors.
  
  
  CONCLUSIONS
  This model may inform studies on the etiology of and changes in complexity, the relationship between complexity and patient outcomes, and intervention development to improve modifiable elements of complex patients.
authors.affiliation: Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, 411 West Chapel Hill Street, Suite 600, Durham, NC, 27701, USA.|Division of General Internal Medicine, Department of Medicine, Duke University Medical Center, Durham, NC, USA.|Duke Cancer Institute, Duke University Medical Center, Durham, NC, USA.|Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.
authors.forename: Leah L
authors.initials: LL
authors.lastname: Zullig
authors.affiliation: Geriatrics Research, Education and Clinical Center, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Division of Geriatrics, Department of Medicine, Duke University, Durham, NC, USA.|Center for the Study of Aging and Human Development, Duke University, Durham, NC, USA.|Depart ment of Ophthalmology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Whitson
authors.affiliation: Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, 411 West Chapel Hill Street, Suite 600, Durham, NC, 27701, USA.|Geriatrics Research, Education and Clinical Center, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Division of Geriatrics, Department of Medicine, Duke University, Durham, NC, USA.|Center for the Study of Aging and Human Development, Duke University, Durham, NC, USA.
authors.forename: Susan N
authors.initials: SN
authors.lastname: Hastings
authors.affiliation: Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.|RTI, Chapel Hill, NC, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Beadles
authors.affiliation: Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Department of Surgery, Duke University Medical Center, Durham, NC, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Kravchenko
authors.affiliation: Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA.|Social Science Research Institute, Durham, NC, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Akushevich
authors.affiliation: Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, 411 West Chapel Hill Street, Suite 600, Durham, NC, 27701, USA. Matthew.Maciejewski@va.gov.|Division of General Internal Medicine, Department of Medicine, Duke University Medical Center, Durham, NC, USA. Matthew.Maciejewski@va.gov.|Ambulatory Care Service, Durham Veterans Affairs Medical Center, Durham, NC, USA. Matthew.Maciejewski@va.gov.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Maciejewski
mesh_terms: D006297:Health Services Accessibility; D006801:Humans; D008962:Models, Theoretical; D005791:Patient Care / Q000379:methods*; D057240:Patient Preference
keywords: complexity; multimorbidity; multiple chronic conditions; patient goal; patients; resilience