New research published Online First in The Lancet shows that having several medical conditions is not just a feature of old age. Most patients with two or more conditions are actually under 65. Health systems in the UK and other developed countries were not devised to deal with this scenario and must be radically changed to cope.

The study was led by Bruce Guthrie, Professor of Primary Care Medicine at Dundee University UK, Stewart Mercer, Professor of Primary Care Research at Glasgow University and lead for the Scottish School of Primary Care research programme on multiple morbidity, Graham Watt, Professor of General Practice at Glasgow University, and colleagues. The study was funded by the Scottish Government Chief Scientist Office.

Management of the rising prevalence of long-term disorders is the main challenge facing governments and health-care systems worldwide. Although individual diseases dominate current approaches to health-care delivery, medical research, and medical education, people with multimorbidity need a broader approach. The use of many services to manage several diseases in one individual can become duplicative and inefficient, and is burdensome and unsafe for patients because of poor coordination and integration.

The authors estimated the burden of multimorbidity, and of comorbidity involving both physical and mental health disorders, in relation to age and socioeconomic deprivation. They took a snapshot of data on 40 common chronic conditions from a database of 1.75 million people registered with 314 medical practices in Scotland. For each of the 40 conditions, people with only that condition were a minority.

They found that around 2 in 5 patients (42%) had one or more conditions, and almost a quarter (23%) had 2 or more and thus had multimorbidity. Although the prevalence of multimorbidity increased substantially with age and was present in most people aged over 65, the absolute number of people with multimorbidity was higher in those under 65 (210 500 vs 195 000).

Importantly, the onset of multimorbidity occurred 10󈝻 years earlier in people living in the most deprived areas compared with the most affluent, with socioeconomic deprivation particularly associated with the combination of physical and mental health disorders. The risk of having a mental health disorder increased as the number of physical morbidities increased. Those with five or more physical conditions were around four times more likely to have a co-existing mental disorder while those in deprived areas were twice as likely to have a co-existing mental disorder as those in affluent areas.

People with multimorbidity are usually excluded from research trials because they are "too complicated", but primary care has no such luxury, excludes no one and is generally left to do the best it can, providing effective care for patients with the most complex combinations of problems. More research is needed on the best ways of providing affordable, comprehensive, personalized, and coordinated continuity of care for people with multimorbidity.

The authors say: "Our findings challenge the single-disease framework by which most health care, medical research, and medical education is configured. Existing approaches need to be complemented by support for the work of generalists, mainly but not exclusively in primary care, providing continuity, coordination, and above all a personal approach for people with multimorbidity. To avoid widening inequality, this approach is most needed in socioeconomically deprived areas, where multimorbidity happens earlier, is more common, and more frequently includes physicalmental health comorbidity."

The Scottish Government's Health Secretary Nicola Sturgeon comments: "This study adds to the large body of evidence we already have that the most vulnerable in our society are more likely to have more than one condition which puts their health at risk.

"The Scottish Government continues to work extremely hard to tackle health inequalities and to improve the health of the population as a whole.

"We are working in partnership with NHS, primary care providers and patients, as well as the research community so that we have effective systems in place to address the needs of people with multiple health conditions and to reduce these health inequalities.

"I look forward to further results coming from the research team, which is assessing a primary care-led approach with patients as a mechanism for improving the health and quality of life of people with multimorbidity, particularly those living in deprived areas of Scotland."

In a linked Comment, Dr Chris Salisbury School of Social and Community Medicine, University of Bristol, UK, says: "the population is ageing, so the proportion of people with several coexisting medical problems is increasing rapidly. Expenditure on health care rises almost exponentially with the number of chronic disorders that an individual has, so increasing multimorbidity generates financial pressures. This economic burden heightens the need to manage people with several chronic illnesses in more efficient ways."

Dr Salisbury suggests that general practitioners in more deprived areas should have lower case loads to account for higher levels of multiple morbidity, and that in hospitals, those with multimorbidity should be assigned to a generalist consultant who would be responsible for coordinating their care.

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More information: Study online: Study online: www.thelancet.com/journals/lancet/article/PII %20S0140-6736(12)60240-2/abstract