Pressure relieving support surfaces: a randomised evaluation

Authors: Nixon J, Nelson EA, Cranny G, Iglesias CP, Hawkins K, Cullum NA, Phillips A, Spilsbury K, Torgerson DJ, Mason S

Journal: Health Technology Assessment Volume: 10 Issue: 22

Publication date: June 2006



Nixon J, Nelson EA, Cranny G, Iglesias CP, Hawkins K, Cullum NA, et al.Pressure relieving support surfaces: a randomised evaluation. Health Technol Assess 2006;10(22)

Download: Citation (for this publication as a .ris file) (5.3 KB)

Journal issues* can be purchased by completing the form.

The cost of reports varies according to number of pages and postage address. The minimum cost for a copy sent to a UK address is £30.00. We will contact you on receipt of your completed form to advise you of actual cost. If you have any queries, please contact

*We regret that unfortunately we are unable to supply bound print copies of Health Technology Assessment published before issue 12:31. However, PDFs are available to print from the "Downloads" tab of the issue page.


No responses have been published. If you would like to submit a response to this publication, please do so using the form below.

Comments submitted to the NIHR Journals Library are electronic letters to the editor. They enable our readers to debate issues raised in research reports published in the Journals Library. We aim to post within 2 working days all responses that contribute substantially to the topic investigated, as determined by the Editors.

Your name and affiliations will be published with your comment.

Once published, you will not have the right to remove or edit your response. The Editors may add, remove, or edit comments at their absolute discretion.

Post your response



Middle Initial

Occupation / Job title

Affiliation / Employer



Other authors

For example, if you are responding as a team or group. Please ensure you include full names and separate these using commas

Statement of competing interests

We believe that readers should be aware of any competing interests (conflicts of interest).

The International Committee of Medical Journal Editors (ICMJE) define competing interests as including: financial relationships with industry (for example through employment, consultancies, stock, ownership, honoraria, and expert testimony), either directly or through immediate family; personal relationships; academic competition; and intellectual passion.

If yes, provide details below:

Enter response title

Enter response message


Security key

Regenerate security key

By submitting your response, you are stating that you agree to the terms & conditions

The full text of this issue is available as a PDF document from the Downloads section on this page.



To determine differences between alternating pressure overlays and alternating pressure replacement mattresses with respect to the development of new pressure ulcers, healing of existing pressure ulcers, patient acceptability and cost-effectiveness of the different pressure-relieving surfaces. Also to investigate the specific additional impact of pressure ulcers on patients' well-being.


A multicentre, randomised, controlled, open, fixed sample, parallel-group trial with equal randomisation was undertaken. The trial used remote, concealed allocation and intention-to-treat (ITT) analysis. The main trial design was supplemented with a qualitative study involving a purposive sample of 20-30 patients who developed pressure ulcers, to assess the impact of the pressure ulcers on their well-being. In addition, a focus group interview was carried out with clinical research nurses, who participated in the PRESSURE (Pressure RElieving Support SUrfaces: a Randomised Evaluation) Trial, to explore the experiences of their role and observations of pressure area care.


The study took place in 11 hospital-based research centres within six NHS trusts in England.


Acute and elective patients aged 55 years or older and admitted to vascular, orthopaedic, medical or care of the elderly wards in the previous 24 hours were investigated.


Patients were randomised to either an alternating pressure overlay or an alternating pressure mattress replacement, with mattress specifications clearly defined to enable the inclusion of centres using products from different manufacturers, and to exclude hybrid mattress systems (which either combine foam or constant low pressure with alternating pressure in one mattress, or can be used as either an overlay or a replacement mattress).

Main outcome measures

Development of a new pressure ulcer (grade < or =2, i.e. partial-thickness wound involving epidermis/dermis only) on any skin site. Also healing of existing pressures ulcers, patient acceptability and cost-effectiveness.


In total, 6155 patients were assessed for eligibility to the trial and 1972 were randomised: 990 to the alternating pressure overlay (989 after one postrandomisation exclusion) and 982 to the alternating pressure mattress replacement. ITT analysis found no statistically significant difference in the proportions of patients developing a new pressure ulcer of grade 2 or above [10.7% overlay patients, 10.3% mattress replacement patients, a difference of 0.4%, 95% confidence interval (CI) -2.3 to 3.1%, p = 0.75]. When logistic regression analysis was used to adjust for minimisation factors and prespecified baseline covariates, there was no difference between the mattresses with respect to the odds of ulceration (odds ratio 0.94, 95% CI 0.68 to 1.29). There was no evidence of a difference between the mattress groups with respect to time to healing (p = 0.86). The Kaplan-Meier estimate of the median time to healing was 20 days for each intervention. More patients allocated overlays requested mattress changes due to dissatisfaction (23.3%) than mattress replacement patients (18.9%, p = 0.02) and more than one-third of patients reporting difficulties associated with movement in bed and getting into or out of bed. There is a higher probability (64%) that alternating mattress replacements are cost-saving; they were associated with lower overall costs (74.50 pounds sterling per patient on average, mainly due to reduced length of stay) and greater benefits (a delay in time to ulceration of 10.64 days on average). Patients' accounts highlighted that the development of a pressure ulcer could be pivotal in the trajectory from illness to recovery, by preventing full recovery or causing varied impacts on their quality of life.


There is no difference between alternating pressure mattress replacements and overlays in terms of the proportion of patients developing new pressure ulcers; however, alternating pressure mattress replacements are more likely to be cost-saving. The results suggest that when renewing alternating pressure surfaces or ordering equipment within a rental contract, mattress replacements should be specified; however, overlays are acceptable if no replacement mattress is available. Similarly, patient preferences can be supported, without any great increase in risk, if individual patients request an overlay rather than a replacement mattress. Further research could include a randomised controlled trial comparing alternating pressure mattress replacements and high-specification foam mattresses in patients at moderate to high risk; an accurate costing study to understand better how much pressure ulcers cost health and social services in the UK; and trials in higher risk groups of patients. Also future trials should measure time to ulceration as the primary end-point, since this is more informative economically and possibly also from a patient and clinical perspective.

Share this page

Email this page
Publication updates

If you would like to receive information on publications and the latest news, click below to sign up.