Quality of care for patients with multiple chronic conditions: the role of comorbidity interrelatedness

Abstract

Multimorbidity--the presence of multiple chronic conditions in a patient--has a profound impact on health, health care utilization, and associated costs. Definitions of multimorbidity in clinical care and research have evolved over time, initially focusing on a patient's number of comorbidities and the associated magnitude of required care processes, and later recognizing the potential influence of comorbidity characteristics on patient care and outcomes. In this article, we review the relationship between multimorbidity and quality of care, and discuss how this relationship may be mediated by the degree to which conditions interact with one another to generate clinical complexity (comorbidity interrelatedness). Drawing on established theoretical frameworks from cognitive engineering and biomedical informatics, we describe how interactions among conditions result in clinical complexity and may affect quality of care. We discuss how this comorbidity interrelatedness influences the value of existing quality guidelines and performance metrics, and describe opportunities to quantify this construct using data widely available through electronic health records. Incorporating comorbidity interrelatedness into conceptualizations of multimorbidity has the potential to enhance clinical and research efforts that aim to improve care for patients with multiple chronic conditions.

Figure 1

Conceptual framework depicting the influence of comorbidity number, characteristics, and interrelatedness on clinical complexity and quality of care for patients. In the proposed framework, the relationship between multimorbidity and quality of care is influenced by a patient’s number of chronic conditions, comorbidity characteristics (e.g., symptom intensity, clinical dominance) and comorbidity interrelatedness, all of which increase clinical complexity. A patient’s sheer number of conditions can generate clinical complexity because of the cognitive burden required to consider multiple clinical issues at once (a). With an increase in number of conditions, there is an increased likelihood that one or more conditions may be symptomatic or dominant due to clinical severity (b), all of which may increase clinical complexity (c) and generate quality of care challenges (d). These condition characteristics also increase the likelihood of conditions interacting with one another in ways that affect management decisions, thereby increasing comorbidity interrelatedness (e). Comorbidity interrelatedness frequently occurs when two conditions are discordant or unrelated in their pathogenesis, but can also occur in the presence of conditions that are asymptomatic and concordant (e.g., diabetes influences the medication of choice for hypertension) (f). Comorbidity interrelatedness can increase clinical complexity through a number of mechanisms, as depicted in the box entitled, “Clinical complexity generated by multimorbidity” (g). Outside of the clinical domain, there are a number of important contextual factors, such as a patient’s behavior, social support, and environment, that can also generate clinical complexity (h) and quality of care challenges (i), and can moderate the relationship between comorbidity interrelatedness and quality of care.

Figure 2

Variation in hypertension management complexity among two individuals with five comorbid conditions, but different levels of comorbidity interrelatedness. This figure illustrates variations in hypertension management complexity for two individuals who each have five hypertension-related comorbidities (conditions for which published clinical evidence and/or guidelines describe interactions with one or more anti-hypertensive classes). ^– Comorbidity interrelatedness varies for Individuals A and B, who have five vs. 16 instances of potential comorbidity–medication interactions (respectively), based on indications and contraindications for one of six common anti-hypertensive classes, and one vs. three instances (respectively) in which the same drug is both indicated and contraindicated on account of their comorbid conditions. *ACE = Angiotensin Converting Enzyme; DHP = Dihydropyridine; Non-DHP = Non-Dihydropyridine.