Multimorbidity, also known as multiple long-term conditions (MLTC), means living with two or more

chronic illness A chronic condition is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term ''chronic'' is often applied when the course of the disease lasts for more than three mo ...

es. For example, a person could have

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, hea ...

and depression at the same time. Multimorbidity can have a significant impact on people's health and wellbeing. It also poses a complex challenge to

healthcare systems Health care or healthcare is the improvement of health via the prevention, diagnosis, treatment, amelioration or cure of disease, illness, injury, and other physical and mental impairments in people. Health care is delivered by health profess ...

which are traditionally focused on individual diseases. Multiple long-term conditions are much more common in older people, affecting more than half of those over 65, however, they can also be found in young people.

Definition

The concept of multiple long-term conditions is not clearly defined and may be referred to by various names.

Difference from comorbidity

Multimorbidity is often referred to as

comorbidity In medicine, comorbidity - from Latin morbus ("sickness"), co ("together"), -ity (as if - several sicknesses together) - is the presence of one or more additional conditions often wikt:co-occur#Verb, co-occurring (that is, wikt:concomitant#Adjecti ...

even though the two are considered distinct clinical scenarios. Comorbidity means that one 'index' condition is the focus of attention, and others are viewed in relation to this. In contrast, multimorbidity describes someone having two or more long-term (chronic) conditions without any of them holding priority over the others. This distinction is important in how the healthcare system treats people and helps making clear the specific settings in which the use of one or the other term can be preferred. Multimorbidity offers a more general and person-centered concept that allows focusing on all of the patient's symptoms and providing a more holistic care. In other settings, for example in pharmaceutical research, comorbidity might often be the more useful term to use.

Definitions

The broad definition of multimorbidity, consistent with what is used by most researchers, the

WHO Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book '' Horton He ...

and the UK's

Academy of Medical Sciences The Academy of Medical Sciences is an organisation established in the UK in 1998. It is one of the four UK National Academies, the others being the British Academy, the Royal Academy of Engineering and the Royal Society. Its mission is to adv ...

is the "''co-existence of two or more chronic conditions''". These can be physical

non-communicable disease A non-communicable disease (NCD) is a disease that is not transmissible directly from one person to another. NCDs include Parkinson's disease, autoimmune diseases, strokes, most heart diseases, most cancers, diabetes, chronic kidney disease, os ...

infectious An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

and mental health conditions in any possible combinations and they may or may not interact with each other. When the co-existing conditions have similar origins or treatments the terms used is ''concordant multimorbidity'', while ''discordant multimorbidity'' is used to refer to conditions that appear to be unrelated to each other. Definitions of multimorbidity usually differ in the minimum number of concurrent conditions they require (most often this is two or more) and in the types of conditions they consider. For example the UK's

National Institute for Health and Care Excellence The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care in England that publishes guidelines in four areas: * the use of health technologies withi ...

(NICE) includes

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

and

substance misuse Substance abuse, also known as drug abuse, is the use of a drug in amounts or by methods which are harmful to the individual or others. It is a form of substance-related disorder. Differing definitions of drug abuse are used in public health, ...

in their list of conditions considered to constitute multimorbidity.

Naming

The most commonly used term to describe the concept is ''multimorbidity''. However, scientific literature shows a diverse range of terms used with the same meaning. These include ''comorbidity'', ''polymorbidity'', ''polypathology'', ''pluripathology'', ''multipathology'', ''multicondition''. The UK's

National Institute for Health and Care Research The National Institute for Health and Care Research (NIHR) is the British government’s major funder of clinical, public health, social care and translational research. With a budget of over £1.2 billion in 2020–21, its mission is to "impr ...

(NIHR) uses the term ''multiple long-term conditions'' (''MLTC'') as it is more accepted and understood by patients and the public.

Causes

Risk factors

A range of biological, psychological, behavioural, socioeconomic and environmental factors affect the likelihood of having multimorbidity. How these

risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...

s interact to trigger multiple long-term conditions is complex and still not fully understood. Lifestyle factors that may increase the risk of multiple long-term conditions include

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...

, poor diet, poor sleep,

smoking Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...

air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...

; and lifestyles factors that may reduce the risk of MLTC includes eating a

healthy diet A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequate fibre and food energy. A healthy ...

, physical activity, and strong social networks. Lower

socioeconomic status Socioeconomic status (SES) is an economic and sociological combined total measure of a person's work experience and of an individual's or family's economic access to resources and social position in relation to others. When analyzing a family's ...

, measured by a combination of education, occupation and literacy indicators, seems to increase the risk of developing multimorbidity. For instance, based on the Whitehall II Study, people in lower employment positions seem to have a 66% higher risk of developing multiple long-term conditions than people in higher positions. However, socioeconomic status does not appear to influence the risk of dying after the onset of multiple long-term conditions. Another study showed an increase of almost 50% in the

odds Odds provide a measure of the likelihood of a particular outcome. They are calculated as the ratio of the number of events that produce that outcome to the number that do not. Odds are commonly used in gambling and statistics. Odds also have ...

of multimorbidity occurring in those with the least wealth compared to those with the most wealth. Therefore, reducing socioeconomic inequalities by improving working and living conditions and

education Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty. Va ...

to everyone is important to reduce the burden of multiple long-term conditions on

population health Population health has been defined as "the health outcomes of a group of individuals, including the distribution of such outcomes within the group". It is an approach to health that aims to improve the health of an entire human population. It ha ...

Diagnosis and impact

Multimorbidity is associated with reduced

quality of life Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards ...

and increased risk of death. The risk of death is positively associated with individuals with greater number of chronic conditions and reversely associated with socioeconomic status. People with multiple long-term conditions may have a four-fold increase in the risk of death in comparison with people without MLTC irrespective of their socioeconomic status. In some cases, specific combinations of diseases are associated with higher mortality. For example, people with long-term conditions affecting the heart, lung, and urinary systems have strong effects on mortality. There are many additional issues associated with living with multiple long term conditions. One study from the US found that having more than 3 conditions significantly increased the chance of reduced

and physical functioning. The researchers called for the holistic treatment of multimorbidities due to the complexities of multiple long-term conditions. Due to the higher prevalence of multimorbidity (55 - 98%), a new concept of "complex multimorbidity (CMM)" has been proposed. CMM differs from the definition of conventional multimorbidity in that CMM is defined by the number of body systems affected by the diseases rather than the number of diseases. CMM is associated is mortality and long-term care needs in older adults.

Mental health

Physical and mental health conditions can adversely impact the other through a number of pathways, and have significant impact on health and wellbeing. For people whose long-term conditions include severe mental illness, the lifespan can be 10–20 years less than the general population. For them, addressing the underlying risk factors for physical health problems is critical to good outcomes. There is considerable evidence that having multiple long-term physical conditions can lead to the development of both depression and

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...

. There are many factors which might explain why physical multimorbidity affects mental health including

chronic pain Chronic pain is classified as pain that lasts longer than three to six months. In medicine, the distinction between Acute (medicine), acute and Chronic condition, chronic pain is sometimes determined by the amount of time since onset. Two commonly ...

, frailty, symptom burden,

functional impairment Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physical, ...

, reduced

, increased levels of

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

, and polypharmacy. Evidence from large population studies from the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

and

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

suggests that specific combinations of physical conditions increase the risk of developing depression and anxiety more than others, such as co-occurring respiratory disorders and co-occurring painful and

gastrointestinal disorders Gastrointestinal diseases (abbrev. GI diseases or GI illnesses) refer to diseases involving the gastrointestinal tract, namely the oesophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the live ...

Healthcare

People with multimorbidity face many challenges because of the way

health system Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...

s are organised. Most health systems are designed to cater for people with a single chronic condition. Some of the difficulties experienced by people with multiple long-term conditions include: poor coordination of

medical care Health care or healthcare is the improvement of health via the prevention, diagnosis, treatment, amelioration or cure of disease, illness, injury, and other physical and mental impairments in people. Health care is delivered by health profess ...

, managing multiple medications (

polypharmacy Polypharmacy (polypragmasia) is the simultaneous use of multiple medicines by a patient for their conditions. Most commonly it is defined as regularly taking five or more medicines but definitions vary in where they draw the line for the minimum ...

), high costs associated with treatment, increases in their time spent managing illness, difficulty managing multiple illness management regimes, and aggravation of one condition by

symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an disease, illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormali ...

or treatment of another. There is growing recognition that living with multiple long-term conditions leads to complex and challenging burdens for people living with MLTC themselves but also health care professionals working in the health system looking after those with long-term conditions. Living with multiple-long term conditions can be burdensome in terms of managing the illness, particularly if the diagnoses results in polypharmacy (taking multiple medicines). The MEMORABLE study sought to understand how to improve medication management for people with MLTC. They identified five burdens that make managing medicines challenging: when the purpose of reviewing medicines is not clear to the person; when a lack of information prevents the person contributing to decisions about their health; when people with MLTC don't see the same health care professional consistently; when people are seen by lots of different professionals working across different services; and when the health service does not recognise the experiences of people living with MLTC.

Prevention

There are well-evidenced prevention strategies for many of the component diseases of multiple condition clusters. For example: *

quitting smoking Smoking cessation, usually called quitting smoking or stopping smoking, is the process of discontinuing tobacco smoking. Tobacco smoke contains nicotine, which is addictive and can cause dependence. As a result, nicotine withdrawal often make ...

- to prevent cardiovascular, respiratory and several neoplastic diseases * a reduction in blood pressure - to prevent coronary disease, ischaemic stroke,

cerebral haemorrhage Intracerebral hemorrhage (ICH), also known as cerebral bleed, intraparenchymal bleed, and hemorrhagic stroke, or haemorrhagic stroke, is a sudden bleeding into the tissues of the brain, into its ventricles, or into both. It is one kind of bleed ...

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...

and

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

, and *

LDL-cholesterol Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall densit ...

lowering - to prevent coronary heart disease and ischaemic stroke. An increased understanding of which conditions most commonly

cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft), a European Space Agency mission to study t ...

, along with their underlying risk factors, would help prioritise strategies for early diagnosis, screening and prevention.

Epidemiology

Multimorbidity is common in older adults, estimated to affect over half of those aged 65 and over. This increased prevalence has been explained by older adults' "longer exposure and increased vulnerability to risk factors for chronic health problems". The prevalence of multimorbidity has been increasing in recent decades. The high prevalence of multimorbidity has led to some describing it as "The most common chronic condition". Multimorbidity is also more common among people from lower

es. Multimorbidity is a significant issue in low‐ and middle‐income countries, although prevalence is not as high as in high income countries.

Research directions

Research funders in the UK, including the Medical Research Council (MRC), the

Wellcome Trust The Wellcome Trust is a charitable foundation focused on health research based in London, in the United Kingdom. It was established in 1936 with legacies from the pharmaceutical magnate Henry Wellcome (founder of one of the predecessors of Glaxo ...

and the National Institute for Health and Care Research (NIHR) have published the "''Cross-funder multimorbidity research framework''" which sets out a vision for the research agenda of multiple long-term conditions. The framework aims to drive advances in the understanding of multiple long-term conditions and promote a change in research culture to tackle multimorbidity. The NIHR also published its own strategic framework regarding MLTC which aligns with the cross-funder framework.

References

External links

Multimorbidity Multimorbidity, also known as multiple long-term conditions (MLTC), means living with two or more chronic illnesses. For example, a person could have diabetes, heart disease and Depression (mood), depression at the same time. Multimorbidity can h ...

in Nature Reviews Disease Primers. {{DEFAULTSORT:Multiple Morbidities Diseases and disorders Public health Epidemiology