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The choice of mattress used in hospital makes no difference to whether adults develop pressure ulcers, or how quickly, but differ on price. This large NIHR-funded trial included 2,029 participants at high risk of developing pressure ulcers and found fewer pressure ulcers overall than expected (7.9%).

Half of about 2,000 participants in this large NIHR-funded trial were given high-specification foam mattresses, the current standard of care, and half used alternating pressure mattresses. The alternating pressure mattresses use pumps to change the pressure in different sections of the mattress and therefore reduce total pressure on any one area over time.

More patients on the alternating pressure mattresses requested a change of mattress because of discomfort or were moved to foam to help with rehabilitation and movement.

Patient preferences and rehabilitation needs should also be considered when choosing a mattress for patients at high risk of developing pressure ulcers.

Why was this study needed?

Pressure ulcers are injuries to the skin and underlying tissue caused by prolonged pressure that restricts adequate blood supply to that area. They are one of the four most commonly reported harms in healthcare, with around 1,700 to 2,000 patients developing them each month. Treating pressure ulcers costs the NHS more than £3.8 million every day. Therefore, preventing pressure ulcers is a priority.

One way of preventing them is by using pressure redistributing devices, which allow capillaries to refill. Specially designed mattresses or cushions are some of the devices tried. Some are more high-tech than others, with higher costs. Before this trial, there were small trials of how effective these devices are, or comparing newer sophisticated devices with older simpler methods. NICE had already recommended that research was needed in this area.

This study aimed to compare the clinical and cost-effectiveness of two common mattress types: the high-specification foam type and the alternating pressure type.

What did this study do?

This randomised controlled trial recruited 2,029 adults from 42 secondary and community inpatient facilities in the UK. All participants were expected to stay in hospital for at least five days and were classified as at high risk for an ulcer by being acutely ill, bedfast or chairfast or having category one pressure pain at a pressure ulcer site.

They were randomised to alternating pressure mattresses or high-specification foam mattresses for a maximum treatment phase of 60 days. The average age of participants was 78 years.

Changes to the skin and development of any pain at pressure points were assessed while they used the mattresses. Skin and pain scores were assessed again 30 days after treatment ended.

The costs assumed for a cost-effectiveness analysis (not reported here) suggest alternating pressure mattresses are more expensive (cost per mattress £3,742 with assumed durability of five years) compared with a specialised foam mattress (cost per mattress £169 with assumed durability of six years).

It was not possible to conceal which group participants were in, due to the appearance of the mattresses.

What did it find?

  • Overall, by the final follow-up, 160 patients (7.9%) developed at least one pressure ulcer categorised as grade 2 or above: 70 (6.9%) in the alternating pressure group, compared with 90 (8.9%) in the high-specification foam group (hazard ratio 0.76, 95% confidence interval 0.56 to 1.04).
  • Grade 2 pressure ulcers took an average of about 18 days (range 2-86 days) to develop on pressure mattresses and 12 days in the foam group (range 2-94 days).
  • A high number of patients also changed group; 24% had at least one mattress change:
    • 90 patients changed as they were uncomfortable on an alternating pressure mattress (40.5%) compared with 28 on a high-specification foam mattress (12.7%).
    • 49 patients were changed to aid rehabilitation or movement while on an alternating pressure mattress (22.1%) compared with 5 on a high-specification foam mattress (2.3%).
    • Three patients on an alternating pressure mattress were changed for clinical reasons (1.4%) compared with 130 on a high-specification foam mattress (59.1%).
  • Only three mattress-related adverse effects were reported.
  • The alternating pressure mattress itself was a significantly more expensive component of in-patient care (£28.80) compared with the high-specification foam mattress (£1.05). However, the main driver for overall costs in the cost-effective analysis was total inpatient care costs.

What does current guidance say on this issue?

NICE published a guideline in 2014 on the prevention and management of pressure ulcers. This recommends using a high-specification foam mattress for all adults who are admitted to secondary care or at high risk of developing a pressure ulcer in primary and community care settings. It also says that high-specification foam mattresses should be used for adults who have a pressure ulcer.

Trusts currently consider the use of a dynamic support surface, such as an alternating pressure mattress, based on clinical circumstances and local guidance.

What are the implications?

Pressure mattresses were equally effective at preventing pressure ulcers in this study.

More patients requested a change from an alternating pressure mattress due to discomfort. In some cases, this type of mattress also made rehabilitation difficult as it can restrict therapist movements compared with foam.

There are cost implications as alternating pressure devices are more expensive than foam mattresses. A separate study has looked at the cost-effectiveness of these mattresses, one compared with the other.

It seems that for now, the choice of mattress type used to prevent pressure ulcers could better take into account patient preferences, rehabilitation needs and risk.

Citation and Funding

Nixon J, Smith IL, Brown S et al. Pressure relieving support surfaces for pressure ulcer prevention (PRESSURE 2): clinical and health economic results of a randomised controlled trial. EClinicalMedicine. 2019;14:42-52.

This project was funded by the NIHR Health Technology Assessment Programme (project number 11/36/33).


McInnes E, Jammali-Blasi A, Bell-Syer SEM et al. Support surfaces for pressure ulcer prevention. Cochrane Database Syst Rev. 2015;(9):CD001735.

NHS Improvement. NHS Safety Thermometer. London: NHS Improvement; 2013.

NHS Improvement. Pressure ulcers: revised definition and management - summary and recommendations. London: NHS Improvement; 2018.

NHS website. Pressure ulcers (pressure sores). London: Department of Health and Social Care; 2017.

NICE. Pressure ulcers: prevention and management. CG179. London: National Institute for Health and Care Excellence; 2014.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre

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