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Multiple long-term conditions – making sense of the evidence

Candace Imison, Associate Director at the NIHR Centre for Engagement and Dissemination, reflects on multiple long-term conditions, the existing evidence and what it offers and the evidence gaps that are left to fill.

Around one in four adults in England, that is more than 14 million people, are now living with two or more health conditions. People with multiple conditions have poorer quality of life and a higher mortality risk. Some combinations are associated with especially poor outcomes; people with severe mental illness live 10 to 20 years less than the general population.

People’s problems do not fit neatly into the current service and professional demarcations. They are much more complex, interdependent and messy. While there is often good bench-to-bedside, vertical integration for single conditions, there is little or no horizontal integration between co-existing diseases. This challenges approaches to research, training, and practice in virtually every discipline.

Addressing these issues is a major strategic priority for the NIHR. We are actively working to develop research culture and practice that moves beyond single diseases and is more holistic in its approach. At the NIHR Centre for Engagement and Dissemination, we aim to make sense of research. Our high level summary of existing evidence on multiple long-term conditions aims to unpack the issues. 

What matters to people with long-term conditions

People with multiple conditions have a wide range of disease profiles and circumstances but they frequently share the same problems. They may have reduced mobility, chronic pain, and lower mental wellbeing. They may be unable to work and have shrinking social networks. Recent research found that people did not talk about diagnoses but instead, spoke movingly about the overall impact on their lives. They described missed opportunities to intervene and the series of losses that add complexity to ill health. 

People with multiple conditions want integrated services, more person-centred, holistic care, and better support for their mental wellbeing. To date, these problems have not been well-addressed by services or research. 

Patient-centred care

The evidence for effective interventions remains sparse. It has often been difficult to demonstrate benefit, possibly because interventions need to be more intense, and carried out for longer than has been done. Improving the quality of life for people with multiple conditions could also be difficult because solutions require actions beyond the remit of healthcare. 

An area of particular importance is the interface between physical and mental health. They are closely interconnected and one can adversely impact the other through a number of pathways

Disease clusters

Better understanding of disease clusters could improve the management of multiple conditions and help set priorities in public health and healthcare. Clusters offer insights into underlying causal mechanisms and disease pathways; better understanding could help in the development of new drugs.  

There are some methodological challenges and the NIHR is investing in a research support facility to help address these. For example, studies have found numerous potential cluster combinations and many people in no distinct cluster category. This has led some to suggest that a generalist or multidisciplinary team approach may be more important than services designed round specific disease clusters. 


Biological, psychological, behavioural, socioeconomic and environmental factors are associated with a higher risk of developing multiple conditions. Deprivation is important, alongside obesity, poor diet, smoking, air pollution and alcohol. Some medications used over time magnify the risk of acquiring another condition, and some diseases increase the risk of others. Biological mechanisms and pathways at the cellular level may trigger other conditions, even when the co-occurring conditions appear unrelated. There are higher rates of multiple conditions in older people, women and those from some ethnic groups.

Evidence on preventive measures is sparse. The importance of deprivation and other public health risk factors means that effective prevention is likely to require population-based strategies that tackle environmental, social and economic factors. 


The rising personal and collective burden of living with multiple conditions poses one of our most significant public health challenges. One made more difficult due to the heterogeneous nature of disease clusters and the complex interactions between different risk factors. The substantial programme of NIHR research informed by what matters most to people with multiple conditions offers hope of improvement.

Candace Imison, Associate Director at the NIHR Centre for Engagement and Dissemination 

Learn more about multiple long-term conditions in our full piece, which aims to make sense of the evidence.

The views and opinions expressed in this blog are those of the authors and do not necessarily reflect those of the NIHR or the Department of Health and Social Care.