Cancer is a chronic disease of aging, with 66 years as the median age of diagnosis in the United States (National Cancer Institute, 2015). As the global population ages, more individuals are diagnosed with multiple health conditions, including cancer. The association between cancer and multimorbidity has implications for cancer prevention, treatment, quality of life, and palliative and end-of-life care (Mazza & Mitchell, 2017). Providers must weigh the risks and benefits of treatment, as well as the risk of increased symptom burden, utilizing guidelines that focus on the cancer diagnosis without considering the complex relationship between cancer and multimorbidity (Sarfati, Koczwara, & Jackson, 2016). Estimates on the prevalence and impact of multimorbidity in patients with cancer vary due to the terminology used in the literature. The lack of consensus and clarity of the concept of multimorbidity makes studying the impact of multimorbidity for patients with cancer difficult. To accurately understand and measure the relationship between multimorbidity and cancer outcomes, healthcare professionals must have a clear understanding of the meaning of multimorbidity in the cancer care setting.
The purpose of this concept analysis is to develop a comprehensive definition for the term multimorbidity in relation to cancer care for use in research and to improve communication of the concept in clinical practice.
Methods:
The framework of Walker and Avant (2011) was used to examine the concept of multimorbidity in cancer care. In September 2018, a search of PubMed was done using the terms cancer, multimorbidity, multiple morbidity, and comorbidity in the title or abstract. Additionally, the Medical Subject Heading terms neoplasms, comorbidity, and multiple chronic conditions were explored. The search was translated into the CINAHL, SocINDEX and PsychINFO databases. No publication time limits were used to ensure the inclusion of early works related to the concept. Additionally, a search for national guidelines related to cancer and multimorbidity, as well as dictionary definitions of multimorbidity, were completed through a Google search. A total of 30 articles were included from nursing, medicine, psychology and sociology.
Results:
The concept of multimorbidity is often used interchangeably with comorbidity. The concept of comorbidity has been defined as an additional disease occurring in an individual with a specific index of disease (Feinstein, 1970). Comorbidity assumes there is a primary disease and there is no assumption of interaction between multiple diseases (Catala-Lopez et al., 2018). In multimorbidity, there is no dominant disease and all health conditions coexist in their potential to burden an individual and present management challenges. Multimorbidity is a more patient-centered construct as it reflects disease burden with all conditions contributing to the overall load (Radner, Yoshida, Smolen, & Solomon, 2014). The National Cancer Institute (NCI) utilizes a cancer-specific comorbidity index developed by Klabunde, Potosky, Legler, and Warren (2000), which builds upon the Charlson Comorbidity Index to assess two-year noncancer mortality for patients with specific health conditions. Utilization of the NCI Comorbidity Index has incorporated the term “comorbidity” in much of the cancer literature to describe individuals with more than one health condition. Factors such as frailty and functional status are viewed as separate constructs, distinctly different from other health conditions (Sarfati et al., 2016). However, research indicates there is a bidirectional relationship between frailty and multimorbidity in older adults (Vetrano et al., 2018). Furthermore, participation in clinical trials for cancer treatment often requires evaluation of a patient’s functional status utilizing the Eastern Cooperative Oncology Group Performance Status scale or Karnofsky Performance Status scale (Cheng, Qureshi, Pullenayegum, Haynes, & Chan, 2017; ECOG-ACRIN, 1982). Patients with reduced or poor physical functioning generally do not meet inclusion criteria for clinical trials.
Based on a systematic review of the literature and applying the concept analysis method of Walker and Avant (2011), the concept of multimorbidity in cancer care can be defined as a patient-centered approach to managing multiple health risks in individuals, while minimizing the impact of disease burden on loss of health and quality of life. A conceptual model of multimorbidity in cancer care reflects the attributes of multiple health risks, disease burden, and a patient-centered approach to care management. The model also incorporates the related concepts of functional status, frailty, quality of life, risk factors, and patient preferences, beliefs and values. The interaction of these attributes and concepts within the patient’s physical and sociocultural environment produce the consequences, or cancer care outcomes.
Conclusion:
Multimorbidity in cancer care is multifaceted and more complex than a sum of health conditions within an individual. As the global population ages, more individuals diagnosed with cancer will present with complex health conditions impacting their care. Current guidelines focus on the treatment of cancer and other diseases in a siloed manner. To improve cancer care outcomes, further research is needed to develop tools that accurately measure multimorbidity in cancer care (Sarfati et al., 2016). Clinical care strategies that reflect a patient-centered approach to multimorbidity in cancer care are needed to improve patients’ health-related quality of life.