The impact of comorbidities on health services


  • Dr Asangaedem Akpan, Consultant Geriatrician, Liverpool University Hospitals NHS Foundation Trust, Visiting Professor, University of Cumbria, Honorary Clinical Associate Professor, University of Liverpool. Tweets at @asanakpan.
  • Dr Kieran Walsh, Clinical Director, BMJ.

Comorbidities are common. In the UK, one in three people who access the health service have two or more chronic conditions. Remarkably, one in three adults admitted to hospital as an emergency in the UK have five or more comorbidities. And comorbidities are associated with a range of adverse effects - on patients and the health service.

People with comorbidities have poorer functional status, quality of life, and health outcomes, and are higher users of ambulatory and inpatient care than are those without comorbidities. When comorbidities aren't taken into account, people get suboptimal care leading to worse clinical outcomes. Comorbidities are also associated with longer lengths of stay. And prolonged lengths of stay are inevitably associated with increased costs.

All of this has a significant effect on health services around the world – including on the NHS. But despite the fact that comorbidities are common and important and, in many ways, add up to something that is more than the sum of their parts, health services have traditionally been built around the needs of people with single conditions. According to Chris Whitty, “training from medical school onwards, clinical teams, and clinical guidelines” “all tend to be organised along single disease or single organ lines.” (1)

The paper by Whitty and colleagues was published in The BMJ in January 2020 – before the outbreak of COVID-19 in the UK.  The COVID-19 pandemic has further exposed the vulnerability of health systems and the issue of people with multiple chronic conditions. In the early months of the pandemic it became clear that those with comorbidities were most affected by the virus. And the comorbidities that increase the risk of severe infection are all common and serious diseases – such as diabetes, heart failure and COPD. Until now, clinical guidelines and decision support tools have largely been based on the assumption that people have single conditions. This has meant that healthcare professionals have lacked guidance and confidence in managing people with multiple chronic conditions presenting with an acute illness.

In light of all of these problems, BMJ Best Practice recently launched a new Comorbidities Tool which has been designed to help with the clinical management of people with multiple chronic conditions presenting with an acute illness. In the tool, static treatment algorithms for clinical management have become dynamic and now change as the clinical condition evolves or changes. This is critical as the clinical management of people with comorbidities is complex and healthcare professionals have to deal with the underlying chronic conditions as well as the acute illness. One example of this is an adult with COVID-19 and comorbidities. Doctors and other healthcare professionals ask themselves complex interrelated questions – such as: What effect will dexamethasone have on diabetes? And on depression? What effect will fluids have on heart failure? What dose of oxygen should I give in light of COPD? Will nebulisers spread the virus? Can I give heparin in light of kidney disease? What about NSAIDs? Do the benefits of ACE inhibitors outweigh the risks? What effect will all these problems have on rehabilitation?

It's a great deal to remember. The good news is that you can now find answers to these questions on the BMJ Best Practice Comorbidities Tool. The content in the tool is evidence-based and is also being continually updated.

The tool acts as a prompt - guiding the healthcare professional as they start treatment for the acute illness. The tool gives guidance on how the various underlying multiple chronic conditions can become unstable and what to do to prevent this. It is also a learning tool especially for clinicians not trained in providing care to adults with multiple chronic conditions. In addition, it can enhance bedside clinical teaching with the lead clinician using it as a teaching aid to cover all the key points for a patient. In the acute setting, it gives clear guidance and confidence to trainees, improves the quality of care, reduces complications and enables the senior review to be more focused.

Competing interests

KW works for BMJ which produces the BMJ Best Practice Comorbidities Tool

AA receives funding to carry out a peer review of the Comorbidities Tool


1. Whitty CJ, MacEwen C, Goddard A, Alderson D, Marshall M, Calderwood C, Atherton F, McBride M, Atherton J, Stokes-Lampard H, Reid W. Rising to the challenge of multimorbidity.

Explore the Comorbidities tool

The BMJ Best Practice Comorbidities tool prompts healthcare professionals to consider a patient’s comorbidities when accessing treatment information on an acute topic. When comorbidities are selected, a tailored patient management plan is produced instantly. Find out more.

Create a COVID-19 treatment algorithm for your patient's comorbidities