Length of stay, comorbidities and mental illness

Author: Dr Kieran Walsh, Clinical Director, BMJ 

Prolonged length of stay in hospital is important for a number of reasons. It results in distress, discomfort and inconvenience for patients. There is an increased risk of nosocomial infections and over treatment. It also results in increased costs to healthcare providers. Yet prolonged length of stay is not an easy problem to solve. Part of the problem is that discharging patients earlier can result in readmission - with an even longer length of stay and even higher costs. 


Multimorbidity contributing to prolonged length of stay

Another means of tackling the problem is to look at what is causing the prolonged length of stay and see if anything can be done about these causes. Multimorbidity is certainly an issue that can cause prolonged length of stay but much of the literature in this regard focuses on chronic non-communicable physical diseases. There have been remarkably few studies on how comorbid mental illnesses can affect length of stay. 

This is all the more reason to look closely at the study by Siddiqui and colleagues which looked at exactly this problem. (1) The study looked at hospital patients with lung or colorectal cancer, chronic obstructive pulmonary disease (COPD), type 2 diabetes, ischaemic heart disease, and stroke. They found that patients with mental health issues illness “incurred higher bed days’ use than for those without mental illness.” They looked at a range of different mental illnesses including disorders due to psychoactive substance use, schizophrenia, mood disorders, and neurotic, stress-related & somatoform disorders. They found that mental illnesses consistently resulted in prolonged length of stay.

The need for more integrated care models and the upskilling of staff

The authors of the study draw a number of conclusions. They state that there is a need for more integrated care models so that patients with physical and mental illnesses will receive better care. They also call for upskilling of staff so that they are better equipped to care for such patients. 

Upskilling of staff will be difficult to achieve in traditional face to face settings in light of current pressures on healthcare and healthcare professional education. It is for these reasons that BMJ has launched the new Comorbidities tool from BMJ Best Practice. This covers mental and well as physical illnesses and features important guidance for patients with physical illnesses who also have depression or dementia. There are multiple examples of this. To take just one example, certain patients with myocardial infarction may also have depression. This will mean healthcare professionals who are managing such patients will have to review any treatment for depression, monitor for hyponatremia, beware of drug interactions, and consider a referral to the liaison psychiatry team. 

It is a lot to remember - which is why clinical decision support that works at the point of care and that provides guidance on how to care for patients with comorbidities is necessary.  


  1. Siddiqui N, Dwyer M, Stankovich J, Peterson G, Greenfield D, Si L, Kinsman L. Hospital length of stay variation and comorbidity of mental illness: a retrospective study of five common chronic medical conditions. BMC health services research. 2018 Dec 1;18(1):498.


Try the new Comorbidities tool from BMJ Best Practice

The Comorbidities tool is the only point of care tool that supports the management of the whole patient by including guidance on the treatment of a patient’s acute condition alongside their pre-existing comorbidities.

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Competing interests
Kieran Walsh works for BMJ which produces the clinical decision support tool BMJ Best Practice.