The prevalence of many diseases increases with age so many older people have more than one illness. Almost two thirds of adults over 80 years of age have three or more chronic diseases. 
In Australia, the prevalence of a chronic condition(s) that accompanies a life-limiting condition is high. For example, 82% for cancer,  90% for chronic obstructive pulmonary disease (COPD),  and 99.1% for heart failure.  Some of the more common conditions include diabetes, heart disease, cancer, hypertension, depression, COPD, stroke, arthritis/osteoarthritis, osteoporosis, and asthma.  The Evidence Synthesis describes some of the more common comorbidities to expect with prevalent life-limiting conditions.
The terms multimorbidity and comorbidity both describe a state of multiple chronic conditions, however, the distinction between the two is starting to be recognised.  In comorbidity, an index condition (e.g. diabetes, stroke, cancer) takes priority and this index condition will often dominate treatment and management decisions. In contrast, multimorbidity is not dominated by an index condition so that all co-existing conditions are regarded equally with none taking priority. 
Progressive diseases like cancer, organ or system failure (e.g. chronic heart failure, chronic obstructive pulmonary disease) and neurological conditions can interfere substantially with life for older adults. In the case of frailty and multimorbidity, predicting when death will occur is often difficult and can impact on timely and person-centred palliative care.
More than 50% of older adults have three or more chronic diseases. Comorbidity and particularly multimorbidity are associated with poorer quality of life, increased use of health services and hospitalisation, and polypharmacy. [1-3] For many older people with multimorbidity, it is likely that at least one of their chronic diseases will be life-limiting and progressive.  The presentation and severity of symptoms will be varied but produce cumulative effects. [2,3,10]
While evidence-based guidelines exist for the management of a single disease, few address comorbidity or multimorbidity particularly in a palliative care context. [2,4] In addition, there is a low inclusion rate of older adults in comorbidity randomised clinical trials which reinforces the difficulty in creating appropriate clinical protocols for their management.  Available guidelines for multimorbidity include:
Clinicians may need to pursue more flexible approaches to care of older adults with co-existing illnesses in a palliative care context where the goals are to provide comfort and maximising quality of life. [4,10] As a person-centred approach to care is central to the Aged Care Quality Standards,  discussions about prognosis can serve as a springboard for difficult conversations with older people with multimorbidity, and may thus facilitate shared or supported decision-making and advance care planning. 
Tools such as Supportive and Palliative Care Indicators Tool (SPICT) and the Gold Standards Framework Prognostic indicator Guidance are available to help with prognostication,  as are established trajectories of decline for major life-limiting illnesses.  However, the dynamic, fluctuating nature of multimorbidity can complicate this. 
Older people with life-limiting illness and multimorbidity may have considerable palliative care needs associated with the cumulative impact of their disease symptoms and functional impairments.  These needs are similar to those of people referred to specialist palliative care.  Therefore, timely identification of palliative care needs is important for improving symptom burden and overall quality of life.
Prioritising treatments requires an assessment across all health issues.  This means considering the person’s co-existing illnesses and the ways in which they and their respective treatments interact. [5,6] It is guided by the person’s clinical and functional status, treatment burden for the person, and the person’s preferences for care. This means providing opportunities for the older person to discuss their quality of life and changing functional ability [2,10] and incorporating their priorities, goals and preferences into shared decisions.  The Instrument for Patient Capacity Assessment (ICAN) Discussion Aid  is a tool which can help patients to discuss treatment burden. It has also been shown to help health professionals understand patient capacity, workload, and treatment burden. 
Integration of these care considerations through supported decision-making is increasingly seen in Australian care settings. Supported decision-making is defined as "the process of enabling a person who requires decision-making support to make, and/or communicate, decisions about their own life. The decision-making is supported, but the decision is theirs.” 
Older adults are particularly prone to adverse drug reactions but despite this, polypharmacy (>5 medications) in the management of multimorbidity is common. [2,22] Regular medication and care plan reviews can help to rationalise medications in light of life expectancy, disease trajectory, and the time it takes for the medication to be affective.  Medications may be therapeutically omitted where burden outweighs benefits. [4,10] A European 7-step process  and a similar Australian five-step process can be used to manage inappropriate polypharmacy.  Both these guidelines advocate consideration of the person’s specific needs and the Australian guidelines encourage consideration of “benefit over the person’s remaining lifespan”, which would include the palliative context. 
Similarly, screening procedures or treatments may be discontinued if the harms and burdens outweigh the perceived benefit. 
Overall the quality of the evidence was acceptable to high [2-4,9,14], although three studies scored poorly [14,15,20,22] due to the lack of reporting on methodology and quality of included studies. These papers were still included in this review due to their relevancy to the topic. Publications other than systematics reviews were included to provide context. [1,5-8,10-12,16-18,21,23]
Page updated 10 May 2022