Pressure ulcers (PUs) are a frequently occurring adverse event in hospitals, especially among immobilised patients (Fremmelevholm and Soegaard, 2019). In Denmark, there are no national data for PU prevalence, but studies at four hospitals between 2002 and 2018 showed a PU prevalence of between 14% and 43% (Bermark et al, 2009). A 2007 European study (5947 patients) across 25 hospitals in Belgium, Italy, Portugal, Sweden and the UK showed a PU prevalence of 18.1% among admitted patients (Vanderwee et al, 2007). At Odense University Hospital (OUH), the prevalence is assessed yearly and a successful quality improvement intervention has reduced the PU prevalence from 10% in 2012 to 2% in 2018 (Fremmelevholm and Soegaard, 2019).
PUs are painful and have severe consequences for patients as well as the economy. In the UK, PUs have been estimated to cost up to 4% of the annual healthcare budget (Bennett et al, 2004). The annual treatment cost of pressure ulcers in the Danish Healthcare System is estimated to be €174.5 million (£154 million) (Mathiesen et al, 2013) Support surfaces, such as mattresses and overlays, play an important role in PU prevention (European Pressure Ulcer Advisory Panel et al, 2014; Nixon et al, 2019). At OUH, alternating-air mattresses (AAM) are used for patients with a medium to high risk of developing PUs. According to a review of randomised controlled trials (RCTs) there are no differences in PU incidence between static mattresses or overlays and AAM (Chou et al, 2013). Qaseem et al (2015) recommended static mattresses or overlays due to their lower costs. Furthermore, AAM are not preferred by patients owing to the reduced ability to move and noise nuisance (Nixon et al, 2019).
The use of AAM was increasing at OUH and, in 2016, the cost of renting AAM was €40 000-48 000 a month. In order to investigate the properties and consequences of implementing static overlays at OUH, a hospital-based health technology assessment (HTA) was conducted. The aim was to investigate the effects of overlays on clinical effectiveness, patient perspectives, and organisational and economic considerations. Owing to confidential information concerning costs of AAM, an economic analysis is not included in this paper.
Methods
Study design, setting and participants
The HTA was based on a literature review and original data from an observational study testing two types of overlays. This article focuses on the observational study. Two types of overlay were tested from August 2017 to January 2018. We used a high-density viscoelastic foam overlay (Tempur - Topper7, TEMPUR-MED, Denmark) and a thermoplastic polyurethane overlay (Stimulite, Zibo Care, Denmark) as alternatives to AAM (Sentry, Hospitech, Denmark). Box 1 gives examples of comparable overlays. For patients with a medium to high risk of developing PUs, the overlays were placed on a standard viscoelastic foam mattress and tested as a supplement to standard care, which was the use of AAM for patients at medium-high risk for PU and standard mattresses for patients not at risk. Thus, there were three types of mattress available during the test period. The overlays were used in a geriatric ward (46 beds) and an orthopaedic ward (23 beds). Each ward had overlay types available for two periods of 3 months as described in Figure 1. PU incidence was investigated in both wards for 7 months (January-July 2017) before the test periods.
The HTA study had four aspects: clinical effect (PU incidence); organisational aspects (staff attitudes); patient perspectives; and economic consequences. However, only the first three parts are included in this paper owing to confidential information in the economic analysis.
Inclusion criteria
All patients admitted to the two wards in the 7 months prior to implementation of the static overlays and for 6 months after the implementation were included in the study. During the test period, patients lying on AAM on arrival at the ward were moved to a bed with an overlay. The optimal support surface for each patient was chosen at admission by ward nurses and/or a specialist wound care nurse based on risk score (Braden scale; Halfens et al, 2000) and clinical assessment. Some high-risk patients and patients with a category 4 PU remained on AAM for clinical reasons.
Patients with PUs at admission were excluded in both periods. Patients lying on a standard mattress on arrival who were moved to a bed with an overlay in the test period were excluded from the study because overlays were meant to replace AAM rather than standard mattresses.
Data sources, variables and analyses
Clinical effectiveness
A specialist wound care nurse examined all admitted patients on the wards for PUs three times a week during the study period and recorded the type of support surface and whether the patient had developed a PU. The average number of hospital days for patients in the two departments was 6 days, and, with examination three times per week, it was possible to examine all patients at the beginning of their hospitalisation and before discharge. Fisher's exact test was calculated using the statistical software package SPSSv24 to investigate statistical difference in PU incidence before and after implementation of overlays.
Organisational perspectives
Staff attitudes were investigated using both a questionnaire survey and semi-structured focus group interviews.
Patient perspectives
Patients' attitudes were investigated in structured in-person interviews by the specialist wound care nurse or an HTA consultant. All patients who had tried both AAM and one overlay, and who were physically and cognitively able were invited to participate. All included patients were aware that they had been lying on both mattresses. Patients were introduced to the investigation and their rights. They were asked which type of support surface they would prefer, followed by questions with defined response categories regarding comfort in relation to softness, noise nuisance, mobility and temperature. Patients also had the opportunity to elaborate on their answers and give further comments.
Ethical approval
Verbal informed consent was obtained from all individual patients included in interviews. No personally identifiable information was recorded. According to our regional ethics committee, this type of study did not require ethical approval.
Results
Clinical effectiveness
In total, 1557 patients were included in the study: 720 patients in the period before implementation (7 months) and 873 patients during the test period (6 months). Some 123 patients used overlays during the study and no statistical difference in PU incidence was found between the periods before and after the implementation of overlays (n=1557, P=0.874) and no patients lying on overlays developed PU (n=123) (Table 1).
| Support surface | |||||
|---|---|---|---|---|---|
| Pressure ulcer incidence | Standard mattress (n) | Alternating-air mattresses (n) | Overlay Tempur (n) | Overlay Stimulite (n) | Total* (n) |
| Before implementation (n=729) | 1.8% (9) | 4.2% (9) | — | — | 2.5% (18) |
| After implementation (n=837) | 2.8% (14) | 4.2% (9) | 0% (0) | 0% (0) | 2.7% (23) |
Organisational aspects
The total response rate for the staff questionnaire survey was 46% (68/147). Of the 68 respondents, 13 had no experience with the overlays, 15 answered both questionnaires (one for each test period) and 40 answered one questionnaire. Thirteen informants participated in focus group interviews: three nurses, four nurse assistants, two physiotherapists, one occupational therapist and three clinical assistants. Table 2 summarises the main results from the two study parts within the different themes.
| Theme | Staff attitude |
|---|---|
| Training in using the support surfaces | Not enough information prior to implementation, more information requested about guidelines for selection of support surface |
| Selection of support surface | 25% of respondents disagreed with the statement: ‘I never have doubts about what type of support surface the patient should lie on.’ However, only 13% thought that the guidelines/criteria were unclear |
| Working procedures and application |
|
| Time spent on tasks affected by support surface | Informants thought nursing was more time consuming for immobile patients lying on overlays, but unchanged for patients who could assist with their own repositioning |
| Work environment | Informants thought immobile patients lying on overlays seemed heavier and more difficult to handle, which could cause long-term physical injuries/discomfort |
| Organisation |
|
| Staff assessment of patient experience |
|
| Satisfaction | 71% of respondents preferred to have overlays as an option for their patients; however, they are not suitable for all patients and AAM are still needed |
Patient perspectives
In total, 12 patients who had tried both an overlay and AAM were interviewed (5 men, 7 women, aged 51–99 years).
All interviewed patients, except one, found the overlays comfortable and none was bothered by the noise. In contrast, some informants mentioned that noise could be bothersome with AAM. Patients answered that it was ‘easy to change position on overlays’ or ‘neither difficult nor easy’, whereas most found it difficult on AAM. With regard to temperature, both AAM and overlays seemed suitable. One patient said: ‘It is easier to move around and it fits me well in regards to softness.’ When asked which type of support surface patients would prefer, all except one preferred overlays. One patient replied: ‘The new mattress is perfect.’
Discussion
Our aim was to investigate the properties and consequences of implementing static overlays based on an observational study comparing AAM with two different types of static overlay. The results showed no statistical difference in PU incidence and none of the patients on overlays developed PUs during the study period. Overall, the patients were satisfied with the overlays, whereas staff had mixed attitudes because there was a change in working procedures. During care and repositioning, sliding material must be used under the patients because they lie more heavily on overlays. After use, the rented AAM are simply rolled up and returned for cleaning and preparation by the company, but the purchased overlays must be cleaned and prepared by the hospital staff. The staff said that cleaning of overlays was more time consuming, and the majority found personal care more difficult for patients who were lying on overlays compared with those on AAM. However, they still preferred overlays as an option and thought that they were beneficial for patients. This could possibly be related to the challenges in repositioning experienced with immobile patients.
There are many studies on the effect of support surfaces for PU prevention, including several reviews (McInnes et al, 2015; Qaseem et al, 2015; Shi et al, 2018). However, in our literature review, we identified only two studies that compared static overlays with AAM on their effect on PU incidence in hospitals (Andersen et al, 1983; Jiang et al, 2014). Both studies were RCTs and our results are in alignment with their findings, that is, there was no significant difference in PU incidence between overlays and AAM. However, Andersen et al was published in 1983 and the support surfaces used then may not be comparable with those used in our study. Both RCTs are of low quality based on the Cochrane risk of bias tool (Higgins et al, 2011) due to ‘unclear risk’ for selection bias (randomisation) in Andersen et al (1983) and unclear risk of ‘performance bias’ (blinding) for both studies.
McInnes et al (2015) and Qaseem et al (2015) had similar results as described above, but they did not distinguish between mattresses and overlays in the comparison with AAM. McInnes et al (2015) found that the majority of included studies comparing AAM with ‘constant low pressure mattresses’ showed no difference in PU prevention and concluded that it was unclear which type of support surface was most beneficial. Similarly, Qaseem et al (2015) concluded that there is no difference between AAM and ‘advanced static’ support surfaces, but recommended static support surfaces due to lower costs. Shi et al (2018) also concluded that it was uncertain which type of support surface was most effective in preventing PUs and that there was a need for RCTs investigating the effect of static foam surfaces with powered active air surfaces, including AAM. Nixon et al (2019) compared AAM with high-specification foam mattresses in an RCT and reported no significant difference in PU prevention.
Based on our results and those from the literature review, there are no clear indications as to which type of support surfaces are most beneficial with respect to PU prevention. Thus, there are no clinical arguments for using AAM rather than overlays in PU prevention, but AAM has been the only option and standard of care for patients at risk of developing PUs at our hospital.
Limitations
This study was an observational comparative study without randomisation and blinding, which affects the internal validity of the study. For example, there may have been an increased focus on PU prevention for patients on overlays and these patients may have been at less risk of developing PU compared with patients on AAM. It was not possible to investigate this further and adjust for any differences in patient groups because we recorded data for PU incidence only. The small number of participants is a limitation of the study.
The staff found overlays more time-consuming to clean and the personal care of patients more difficult compared with the use of AAM. This could have affected their responses. The results are uncertain, but in alignment with the results of other studies. We focused on the use of two types of overlay, but there may be other, more beneficial, alternatives to AAM.
Conclusion
Despite limitations, the results of the HTA show that overlays are a suitable alternative to AAM for patients with a medium to high risk of developing PUs, since no difference in PU incidence was found and no patients on overlays developed PUs. Furthermore, patients, as well as staff, preferred having overlays as an option. However, the overlays are not suitable for all patients and clear guidelines on the selection of support surfaces are necessary. Organisational challenges, such as more time spent on cleaning, should be taken into consideration before implementation.
Further investigation of the economic aspects of using overlays is needed because there could be possible financial benefits.