Table 2.
Summary characteristics of included studies
| Study | Study design | Location | Population focus | Assessment of multimorbidity (presence/ nature/extent/ both) | List of chronic conditions | Measure of socioeconomic disadvantage |
| Andersén et al79 | Cross-sectional | Finland | Adults aged 20–69 years | Presence of multimorbidity. Cut-off of two conditions. |
18 chronic conditions including: respiratory diseases, cardiovascular diseases, diabetes, mental disorders, dyspepsia/reflux disease, chronic kidney failure, sleep apnea, osteoporosis and chronic pain. | Occupation. |
| Calvo et al58 | Longitudinal | USA | Adults aged 60–61 and 70–71 years | Count of chronic conditions. | Eight conditions including high blood pressure, diabetes, cancer, chronic lung disease, heart problems, stroke, mental illness, arthritis or rheumatism. | Retirement sequence. |
| Craig et al41 | Cross-sectional | Jamaica | Individuals aged 15–74 years | Patterns of multimorbidity. | 11 chronic conditions including hypertension, obesity, hypercholesterolemia, diabetes, asthma, arthritis, cardiovascular disease, mental health disorders, COPD, stroke and glaucoma. | Occupational status, education and income level. |
| Head et al62 | Longitudinal | England | Adults aged 18 years and over | Presence of multimorbidity. Cut-off of two and three conditions. |
211 conditions listed elsewhere.62 | Area-level deprivation. |
| Hernández et al77 | Cross-sectional | 4 high income countries | Adults aged 52–85 years | Patterns of multimorbidity. | 10 conditions including cardiovascular diseases, diabetes, arthritis, cancer, lung disease, osteoporosis and psychological disorders. | Education, household income and employment. |
| Hone et al52 | Cross-sectional | Brazil | Individuals of any age | Presence of multimorbidity. Count of chronic conditions. |
53 chronic conditions. | Education. |
| Khanolkar et al64 | Longitudinal | UK | Adults aged 36–69 years | Presence of multimorbidity. Count of chronic conditions. |
18 health conditions including metabolic conditions, cardiovascular diseases, cancer, respiratory disorders, kidney disorders, gastrointestinal disorders, skin disorders, osteoarthritis, rheumatoid arthritis, neurological disorders and mental disorders. | Social class and education. |
| Lee et al67 | Longitudinal | South Korea | Adults aged 45 years and over | Multimorbidity clusters. Cut-off of two conditions. |
9 chronic conditions including: hypertension, diabetes, cancer, chronic lung disease, liver disease, heart disease, cerebrovascular disease, arthritis or rheumatoid arthritis and depression | Education, household income and employment. |
| Moin et al90 | Cross-sectional | Canada | Adults aged 22–95 years | Presence of multimorbidity. Cut-off of two and three conditions. |
18 chronic diseases including cardiovascular diseases, respiratory conditions, diabetes, mental illness, musculoskeletal conditions, renal failure, inflammatory bowel failure and cancers. | Household income and education. |
| Zacarías-Pons et al75 | Longitudinal | Europe | People aged 50 years and older | Latent transition analysis for types of multimorbidity. | Heart attack, hypertension, hypercholesterolaemia, stroke or cerebral vascular disease, diabetes or high blood sugar, chronic lung disease (COPD), cancer, stomach or duodenal ulcer, Parkinson disease, cataracts, dementia, other affective or emotional disorders, rheumatoid arthritis, osteoarthritis and osteoporosis | Education, employment and material deprivation index. |
| Vidyashree et al 48 | Cross-sectional | India | People aged 60 years and above in rural area | Presence of multimorbidity (cut-off unclear). |
Unclear. | Economic dependency. |
| Sharma and Maurya47 | Cross-sectional | India | People aged 60 years and above | Presence and patterns of multimorbidity. Cut-off of two conditions. |
Arthritis, rheumatism or osteoarthritis, cerebral embolism stroke or thrombosis, heart diseases, diabetes, chronic lung disease, asthma, depression, hypertension, Alzheimer’s disease, cancer, dementia, liver or gall bladder illness, osteoporosis, renal or urinary tract infection, cataract, loss of all-natural teeth, accidental injury in the past 1 year, injury due to fall, skin disease and paralysis. | Educational attainment, working status and wealth quintile. |
| Singh et al72 | Longitudinal | Australia | People aged 15 years and above | Presence of multimorbidity. Cut-off of two conditions. |
Arthritis, cancer, type 1 diabetes mellitus, type 2 diabetes mellitus, hypertension, heart disease, asthma, bronchitis or depression. | Financial hardship. |
| Aminisani et al56 | Longitudinal | New Zealand | Adults aged 55–70 years | Presence of multimorbidity. Cut-off of two conditions. |
Nine groups of chronic diseases: cardiovascular diseases, neurological diseases, musculoskeletal conditions, diabetes mellitus, respiratory diseases, chronic liver conditions, cancer and mental disorders. | Education and income. |
| Chamberlain et al83 | Cross-sectional | USA | Adults aged 20 years and over | Presence of multimorbidity. Cut-off of two conditions. |
21 conditions including cardiovascular diseases, metabolic conditions, respiratory diseases, arthritis, osteoporosis, chronic kidney disease, autism spectrum disorder, hepatitis, HIV, depression, dementia, schizophrenia and substance. | Area level deprivation. |
| Costa et al39 | Cross-sectional | Brazil | Adults aged 20–59 years | Presence of multimorbidity. Cut-off of two conditions. |
14 conditions including cardiovascular diseases, metabolic diseases, chronic pulmonary disease, digestive disorders, neurological disorders, cancer, kidney disease and depression. | Economic status and education. |
| Kim et al66 | Longitudinal | South Korea | Adults aged 19 years and over. | Presence of multimorbidity. Cut-off of two conditions. |
28 chronic conditions as listed elsewhere.63 | Household income and education. |
| Møller et al68 | Longitudinal | Denmark | People aged 16 years and over | Multimorbidity patterns or classes (Latent Class Analysis). | 47 diseases. | Education and employment. |
| Odland et al45 | Cross-sectional | Burkina Faso | Adults aged 40 years and older | Presence and patterns of multimorbidity. Cut-off of two conditions. |
11 conditions including: cancer, HIV, chronic respiratory disease, stroke heart disease, hypertension, diabetes, anxiety, depression and dementia/cognitive decline. | Education and wealth. |
| Pati et al46 | Cross-sectional | India | Adults aged 18 years and older | Presence of multimorbidity. Cut-off of two conditions. |
21 chronic conditions. | Poverty level and education. |
| Zhao et al50 | Longitudinal | China | People aged 50 years and older | Presence of multimorbidity. Cut-off of two conditions. |
Diagnosed. | Annual per-capita household consumption. |
| Yildiz et al85 | Cross-sectional | The Netherlands | People aged 18–64 years | Presence of multimorbidity. Cut-off of two and three conditions most prevalent chronic diseases |
List of most prevalent chronic diseases (cardiovascular diseases, psychological disorders, inflammatory conditions and respiratory diseases). | Employment status and education. |
| Wister et al82 | Cross-sectional | Canada | People aged 45–85 years | Presence of multimorbidity. Cut-off of two conditions. |
High blood pressure, osteoarthritis, back problems, cancer, diabetes, heart disease, thyroid dysfunction, lung disease, osteoporosis, urinary incontinence, migraine headaches, irritable bowel syndrome, intestinal and stomach ulcer, glaucoma, peripheral vascular disease, angina, macular degeneration, heart attack, transient ischaemic attack, kidney disease, rheumatoid arthritis, bowel incontinence, stroke, multiple sclerosis, epilepsy, Parkinson’s disease, as well as dementia and Alzheimer’s disease. | Vancouver. |
| Vinjerui84 | Cross-sectional | Norway | People aged 25–100 years | Complex multimorbidity. Three or more diseases involving three or more different body (organ) systems. |
51 chronic conditions including following body systems or types: neoplasms, endocrine/nutritional/metabolic, mental/behavioural, eye/adnexa, ear/mastoid, circulatory system, respiratory system, digestive system, skin/subcutaneous tissue, musculoskeletal/connective tissue and genitourinary systems. | Occupational groups. |
| Ba et al36 | Cross-sectional | Vietnam | Individuals aged 15 years and over | Presence of multimorbidity. Cut-off of two conditions. |
A list of 11 conditions including: cancer, heart and circulatory conditions, chronic joint problems, chronic pulmonary diseases, chronic kidney problems, chronic digestive problems, psychological illness, diabetes, and/or other chronic conditions (such as eye, nose, sore and throat, teeth problems, etc). | Educational level and occupational status. |
| Dugravot et al60 | Longitudinal | UK | Adults aged 35–55 years | Presence of multimorbidity. Cut-off of two and five conditions. |
9 conditions including diabetes, coronary heart disease, stroke, COPD, depression, arthritis, cancer, dementia and Parkinson’s disease. | Occupational position, education. |
| Johnston et al63 | Longitudinal | Scotland | Adults aged 45–51 years | Presence of multimorbidity. Cut-off of two conditions. |
Six conditions. List not provided. | Father’s occupation during childhood. Educational attainment in adulthood. |
| Park et al69 | Longitudinal | South Korea | Adults aged 50 years and older | Presence and patterns of multimorbidity (LCA). Cut-off of two conditions. |
10 chronic diseases: hypertension, dyslipidaemia, stroke, osteoarthritis, tuberculosis, asthma and allergies. | Household income, educational level and occupation. |
| Russell et al55 | Longitudinal | New Zealand | Age 2 years | Presence of multimorbidity. Cut-off of two conditions. |
Asthma requiring medication, eczema requiring medication, a birth condition, epilepsy, permanent hearing problems, vision problems not correctable with glasses and obesity. | Index constructed from maternal education, employment, financial stress, beneficiary status, housing tenure, overcrowding and residential mobility. |
| Seo71 | Longitudinal | South Korea | Working age adults | Presence of multimorbidity. Cut-off of two conditions. |
23 conditions. | Type of employment, income and education. |
| Calderón-Larrañaga et al57 | Longitudinal | Sweden | Adults aged 60 years and over | Presence of multimorbidity was explored as rapid or slow development of multiple chronic conditions. Cut-off of two conditions. |
List not provided. A disease was considered chronic if it had a long and if residual disability remained or life quality was worsened or long period of care, treatment or rehabilitation was needed. | Educational level and occupation. |
| Costa et al40 | Cross-sectional | Brazil | Adults aged 60 years and over | Presence and nature of multimorbidity. Cut-off of two conditions. |
31 conditions: cardiovascular diseases, metabolic conditions, musculoskeletal conditions, incontinence and constipation, neurological diseases, mental disorders, cancer, respiratory diseases and kidney disease. | Educational level and monthly income per capita (National Economic Index). |
| Mondor et al80 | Cross-sectional | Canada | Adults aged 18 years and older | Presence of multimorbidity. Cut-off of two conditions. |
12 chronic conditions including high blood pressure, diabetes, osteoarthritis, rheumatoid arthritis, heart attack, stroke, cancer, chronic lung disease, hip fracture, Parkinson’s disease, Alzheimer’s disease and affective disorders. | Household income and educational level inequalities. |
| Stanley et al3 | Cross-sectional | New Zealand | Adults aged 18 years and older | Presence of multimorbidity. Cut-off of two conditions. |
List of diseases not provided but listed elsewhere.64 | Area-based measure of socioeconomic deprivation |
| Stokes et al91 | Cross-sectional | New Zealand | Pacific and Maori adults aged 35 years and older | Presence of multimorbidity. Cut-off of two conditions. |
31 chronic conditions. | Area based measure of socioeconomic deprivation. |
| Alimohammadian et al35 | Cross-sectional | Iran | Adults aged 40–75 years | Presence of multimorbidity. Cut-off of two conditions. |
A total of nine conditions were explored: cardiovascular disease, diabetes (types I and II), COPD, chronic liver disease, tuberculosis, gastro-oesophageal reflux disease and cancers. | Socioeconomic status. Education. |
| Canizares et al59 | Longitudinal | Canada | Adults aged 20–69 | Presence and extent of multimorbidity. Cut-off of two conditions. |
18 chronic conditions were explored: arthritis, back problems, respiratory conditions, allergies (excluding food allergies), cardiovascular diseases, diabetes, cancer, ulcers, urinary incontinency, dementia, migraine, glaucoma and cataracts. | Education and household income. |
| Hayek et al61 | Longitudinal | Israel | Adults aged 21 years and over | Presence of multimorbidity. Cut-off of two conditions. |
10 conditions were assessed: asthma, arthritis, cancer, diabetes, dyslipidaemia, heart attack, hypertension, migraine, osteoporosis or thyroid disease. | Monthly household income and years of schooling. |
| Katikireddi et al10 | Longitudinal | Scotland | Adults aged 35–75 years | Presence and extent of multimorbidity. Cut-off of two conditions. |
40 conditions. | Area-based deprivation level. |
| Ki et al65 | Longitudinal | South Korea | Adults aged 30 years and over | Presence and extent of multimorbidity. Cut-off of two conditions. |
66 chronic conditions. | Educational attainment, employment status and relative poverty index. |
| Nielsen et al92 | Cross-sectional | 15 European countries | Adults aged 50 years and over | Presence of multimorbidity. Cut-off of two conditions. |
13 chronic conditions: high blood pressure, diabetes, osteoarthritis, rheumatoid arthritis, heart attack, stroke, cancer, chronic lung disease, hip fracture, Parkinson’s disease, Alzheimer’s disease and affective disorders. | Education and household income. |
| Nunes et al12 | Cross-sectional | Brazil | Adults aged 18 years and over | Presence of multimorbidity. Cut-off of two conditions. |
21 chronic conditions including: cardiovascular diseases, respiratory conditions, mental disorders, musculoskeletal conditions, metabolic disorders, arthritis/rheumatism, cancer and kidney problem. | State level of education and wealth quintiles. |
| Puth et al81 | Cross-sectional | Germany | Adults aged 18 years and older | Presence of multimorbidity. Cut-off of two conditions. |
15 chronic diseases: hypertension, coronary heart disease, myocardial infarction, chronic heart failure, stroke, diabetes mellitus, bronchial asthma, any type of cancer, hypercholesterolaemia, chronic bronchitis, chronic liver disease, arthrosis, osteoporosis, arthritis and depression. | Level of education. |
| Congdon93 | Cross-sectional | London, UK | Adults aged between 65 and 75 years | Presence of multimorbidity. Cut-off of two conditions. |
A list of 15 chronic conditions were assessed: cardiovascular diseases, diabetes, asthma, COPD, dementia, depression, serious mental illness (psychosis or bipolar disorder), cancer and chronic kidney disease. | Area-level socioeconomic deprivation. |
| Garin et al43 | Cross-sectional | 9 low to upper middle-income countries | Adults aged 50 years of age | Presence of multimorbidity. Cut-off of two conditions. |
9 conditions explored: arthritis, asthma, cataract, COPD, depression, diabetes, edentulism, hypertension, cognitive impairment, obesity and stroke. | Household income and education. |
| Jackson et al9 | Longitudinal | Australia | Women aged 45–50 years | Multimorbidity patterns (psychosomatic, musculoskeletal, cardiometabolic, cancer and respiratory syndromes). | 23 conditions examined including cardiovascular diseases, musculoskeletal conditions, respiratory diseases, cancer, allergies, mental conditions, diabetes, impaired glucose tolerance and chronic fatigue syndrome. | Education, occupation and income management. |
| Tomasdottir et al73 | Longitudinal | Norway | Adults aged 20–59 years | Presence of multimorbidity. Cut-off of two conditions. |
17 chronic conditions. | Financial hardship (worries). |
| Afshar et al34 | Cross-sectional | 28 low-income to middle-income countries | Adults aged 18 years and over | Presence of multimorbidity. Cut-off of two conditions. |
Seven chronic conditions including: arthritis, angina pectoris, asthma, depression, schizophrenia or psychosis and diabetes. | Level of education. |
| Chung et al38 | Cross-sectional | China | Adults aged 15 years and older | Presence and extent of multimorbidity. Cut-off of two conditions. |
List not provided. | Household income, educational attainment, employment status and type of housing. |
| Diaz et al94 | Cross-sectional | Norway | Immigrants aged 15 years and over | Presence of multimorbidity. Cut-off of two conditions. |
List not provided. | Personal income level. Reason for migration. |
| Prazeres and Santiago,95 | Cross-sectional | Portugal | Adults aged 18 years and older | Extent and presence of multimorbidity. Cut-off of two and three conditions. |
List not provided. | Years of educations, professional status and self-perceived socioeconomic status. |
| Roberts et al96 | Cross-sectional | Canada | Adults aged 20 years and older | Presence and extent of multimorbidity. Cut-off of three or three conditions. |
A list of nine conditions including arthritis, mood disorder and/or anxiety, asthma, diabetes mellitus, heart disease, COPD, cancer, stroke, and Alzheimer’s disease. | Educational level and household income. |
| Banjare and Pradhan37 | Cross-sectional | India | Adults aged over 60 years | Extent of multimorbidity (no morbidity, one morbidity, two morbidities and three or more morbidities). | 23 chronic conditions were assessed: musculoskeletal conditions, cardiovascular disease, respiratory conditions, neurological disorders, severe dental conditions, kidney or renal disorders, depression, liver or gall bladder illness, accidental injury, injury due to fall and skin disease. | Education, state of economic independence, quintiles of wealth, living arrangement and caste. |
| Habib et al44 | Cross-sectional | Lebanon | Palestinian refugees aged between 14 and 87 years old | Presence and extent of multimorbidity. Cut-off of two conditions. |
List not provided. | Educational attainment and wealth index. |
| McLean et al78 | Cross-sectional | Scotland | Adults aged 25 years and over | Presence and pattern of multimorbidity (physical only, mental only and mixed physical and mental multimorbidity). Cut-off of two conditions. |
A list of 35 physical and eight mental conditions were included but not specified on the paper. | Area-based deprivation. |
| Violán et al97 | Cross-sectional | Spain | Adults aged 19 years and older | Presence of multimorbidity. Cut-off of two conditions. |
31 chronic conditions. | Area-level of deprivation. |
| Alaba and Chola51 | Cross-sectional | South Africa | Adults aged 18 years and over | Presence or absence of multimorbidity. Cut-off of two conditions. |
Eight chronic conditions were assessed including tuberculosis, high blood pressure, diabetes or high blood sugar, stroke, asthma and cancer. | Years of schooling, household income, social assistance and employment. |
| Cornish et al54 | Longitudinal | Bristol, UK | Children aged 0–18 years | Presence and extent of multimorbidity. Cut-off of two conditions. |
As listed in the Johns Hopkins University Adjusted Clinical Groups System. | Parent’s educational level. Occupational social class. Housing tenure. Family adversity index during pregnancy. Area socioeconomic deprivation. |
| Demirchyan et al42 | Longitudinal | Armenia | Adults aged 37–90 years | Presence of multimorbidity. Cut-off of two conditions. |
List not provided. | Education, perceived low affordability of healthcare services and perceived living standards. |
| Weiman et al49 | Cross-sectional | South Africa | People aged 15 years and older | Presence of multimorbidity. Cut-off of two conditions. |
List not provided. | Multidimensional poverty index. |
| Agborsangaya et al86 | Cross-sectional | Canada | Adults aged 18 years and over | Presence of multimorbidity. Cut-off oftwo conditions. |
>16 chronic conditions explored, including diabetes, respiratory conditions, cardiovascular diseases, depression or anxiety, chronic pain, arthritis, gastrointestinal tract disease and kidney diseases. | Educational level and annual household income. |
| Barnett et al53 | Cross-sectional | UK | Individuals from all ages | Presence of multimorbidity Cut-off of two conditions. |
40 chronic conditions. | Area-level deprivation. |
| Schäfer et al70 | Longitudinal | Germany | Adults aged 65 years and older | Presence and patterns of multimorbidity (cardiometabolic disorders and anxiety, depression, somatoform disorders and pain) Cut-off of three conditions. |
29 chronic conditions. | Education, autonomy on former occupation and household income. |
| Tucker-Seeley et al74 | Longitudinal | USA | Adults aged 50 years and over | Presence and extent of multimorbidity. Count of chronic conditions. |
Six chronic conditions: cancer, heart disease, lung disease, stroke, diabetes and hypertension. | Childhood financial hardship (yes/no). Average lifetime earnings during young and middle adulthood. Educational attainment as indicator of adult socioeconomic status. |
COPD, chronic obstructive pulmonary disease.