Evid Based Nurs 10:23 doi:10.1136/ebn.10.1.23
  • Economics

Alternating pressure mattresses were more cost effective than alternating pressure overlays for preventing pressure ulcers

 Q What is the relative cost effectiveness of alternating pressure mattresses and alternating pressure overlays for preventing pressure ulcers in hospital patients with limited mobility?



randomised controlled trial (RCT).


10 hospitals in the UK.


1972 patients ⩾55 years of age (mean age 75 y, 64% women) admitted to vascular, orthopaedic, medical, or elderly care wards in the previous 24 hours, with an expected hospital stay of ⩾7 days and limited activity and mobility (Braden scores of 1 or 2) or existing grade 2 pressure ulcer. Elective surgical patients were included if they were expected to have limited mobility for ⩾3 days postoperatively. Exclusion criteria included ⩾ grade 3 pressure ulcer, planned admission to intensive care ward after surgery, sleeping at night in a chair, and weight <45 kg or >140 kg.


alternating pressure overlay (n = 990) or alternating pressure mattress (n = 982) for duration of ward stay or until mobility improved to a Braden score of 3 or 4.


pressure ulcer free days (time to development of a new pressure ulcer ⩾ grade 2), length of hospital stay, hospital costs.


Purchase costs were £1011 for the overlay and £4174 for the mattress (£1.38 and £5.71/d, respectively, assuming a 2 year lifespan of both devices). Daily hospital costs were £165–385/day, depending on specialty. Use of the alternating pressure mattress resulted in an average of 11 more pressure ulcer free days and 1.2 fewer days in hospital than use of the alternating pressure overlay. Overall hospital costs were lower for the mattress (table). The difference in costs remained similar when considering a 5 or 7 year lifespan rather than 2 years, or equipment rental rather than purchase (table).


In hospital patients with limited mobility, use of alternating pressure mattresses was associated with a delay in pressure ulcer development and lower hospital costs.


  1. Annette Hoskins, RN, MN, MRCNA
  1. Department of Nursing, University of Wollongong
 Wollongong, New South Wales, Australia

      Pressure relieving support surfaces are widely used to prevent pressure ulcers. These surfaces range from foam mattresses for standard use in vulnerable patients to alternating pressure mattresses for high risk patients. A Cochrane systematic review of 41 RCTs assessed the effectiveness of different pressure relieving surfaces in preventing pressure ulcers and found no clear evidence to support the use of any specific surface.1 This result provided the stimulus for the RCT by the UK PRESSURE Trial Group. No previous trial has compared an alternating pressure mattress with an alternating pressure overlay, in terms of pressure ulcer prevention or cost effectiveness. The studies by Iglesias et al and Nixon et al report different outcomes from the same RCT; the study was designed to test both effectiveness and cost effectiveness.

      The findings of Nixon et al clearly showed no difference between alternating pressure mattresses and overlays in overall pressure ulcer development. However, Iglesias et al showed that although overlays were cheaper to purchase (approximately 25% of the cost), mattresses were more cost effective in terms of delayed time to pressure ulceration and patient acceptability.

      The execution of the RCT was as methodologically rigorous as possible, given that it incorporated nurses’ ethical decisions on the “best” intervention for individual patients (eg, using a mattress rather than an overlay because of perceived high risk of the patient). It is feasible that mattresses provide the “best” protection when considering purchase cost, brand desirability, and expected quality. More patients in the overlay group requested a change of surface because of discomfort.

      Strengths of the trial include the large sample of 1972 patients from various locations and specialities and the use of clinically relevant inclusion criteria. The emphasis on the prevention of pressure ulcers was positive. The Braden Scale for risk assessment was a good choice, with reasonable sensitivity and specificity for most at-risk patient groups.

      Some potential issues and unknown factors in the trial should be considered. Firstly, variations in brands, quality, maintenance, and age of alternating pressure mattresses and overlays would exist within the stocks of different institutions. However, this situation models the reality of health care, and the trial was testing the effect of a policy of pressure prevention as much as it was evaluating pressure devices. Secondly, because care providers were not blinded to patient allocation, questions arise as to whether patients were handled or turned at the same intervals in the mattress and overlay groups. Again, because this was a pragmatic trial, it is likely that any variations in turning were distributed evenly between the groups. Thirdly, Iglesias et al reported that additional treatment costs were not estimated when a stage 2 pressure ulcer was detected; thus, treatment costs may be underestimated.

      Despite these limitations, the findings of the PRESSURE trial are a welcome addition of knowledge that can assist healthcare providers in making decisions about purchasing and using pressure relieving devices. Convincingly, the authors believe that the best decision would be for hospitals to use mattresses instead of overlays in acutely ill patients who are deemed “at risk.” The crucial point, as stated by Iglesias et al, is that the longer patients avoid ulceration, the less likely they will be to develop a pressure ulcer as their mobility improves.


      Alternating pressure mattresses v alternating pressure overlays for preventing pressure ulcers in hospital patients with limited mobility

 Q What is the relative cost effectiveness of alternating pressure mattresses and alternating pressure overlays for preventing pressure ulcers in hospital patients with limited mobility?


      • For correspondence: Professor N Cullum, University of York, York, UK. nac2{at}

      • Source of funding: Health Technology Assessment Programme of the UK Department of Health.

      Free Sample

      This recent issue is free to all users to allow everyone the opportunity to see the full scope and typical content of EBN.
      View free sample issue >>

      EBN Journal Chat

      The EBN Journal Chat offers readers the opportunity to participate in discussion about research articles and commentaries from Evidence Based Nursing (EBN).

      How to participate >>

      Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.

      Navigate This Article