Interest in multimorbidity -commonly defined as the co-occurrence of at least two chronic conditions in the same individual 1 -has increased in the past few years owing to its substantial effect on the individual and the individual's family, as well as on health systems and on society, particularly in resource-poor settings 2-4 . Multimorbidity is distinct from the related concept of comorbidity, which refers to the combined effects of additional conditions in relation to the index condition in an individual [5][6][7][8] . By contrast, care for multimorbidity is patient-centred and does not routinely give priority to any single condition, although in clinical care, patients and clinicians will usually focus on the most pressing problems that the patient is experiencing.People with multimorbidity are more likely to die prematurely, be admitted to hospital and have an increased length of stay than people with a single chronic condition 9,10 . Multimorbidity is also associated with poorer function and health-related quality of life (HRQOL), depression and intake of multiple drugs (polypharmacy) and greater socioeconomic costs [11][12][13][14][15][16][17][18] . Most health care is designed to treat individual conditions rather than providing comprehensive, person-centred care 2,19,20 , which often leads to fragmented and sometimes contradictory care for people with multimorbidity and increases their treatment burden 21 Moreover, treating one condition at a time is inefficient and unsatisfactory for both people with multimorbidity and their health-care providers [22][23][24] .Multimorbidity is increasingly common owing to changes in lifestyle risk factors, notably physical inactivity and obesity, and population ageing that in part reflects improvements in survival from acute and chronic conditions 2,19,25,26 . Multimorbidity is associated with socioeconomic status and age 3,19,25,27 . However, although age is the strongest driver of multimorbidity, in absolute numbers, more people <65 years of age have multimorbidity than people ≥65 years of age, partly because more people in the general population are in that age group. Moreover, this emphasizes that multimorbidity is not just a feature of ageing 19,26 .Multimorbidity is further complicated in low-income and middle-income countries (LMICs) by the overlap of compounding factors, including adverse environmental and early life stressors linked to poverty, limited social infrastructure and poorer family coping mechanisms, that translate into chronic diseases occurring at earlier ages [28][29][30][31] . LMICs also have a higher prevalence of multimorbidity-related financial burden 32,33 and have weaknesses in health systems including a greater focus
Treatment burdenThe workload associated with managing treatments and health-care recommendations and the impact of this on an individual and their supporters.