4 Committee discussion

Clinical-effectiveness overview

SEM Scanner 200 can reduce pressure ulcer incidence but there are considerable uncertainties

4.1 The committee noted that the published evidence suggested that using SEM Scanner 200 could result in statistically significant reductions in pressure ulcer incidence. But the clinical experts explained that the size of this benefit was greater than they would expect from their own clinical experience. One clinical expert commented that using SEM Scanner 200 had substantially reduced pressure ulcer incidence in their hospice, but not to the same degree as reported in the studies. The committee also considered that it was unclear from the studies whether reduced pressure ulcer incidence was because of:

  • the scanner results guiding care management decisions or

  • increased attention to pressure ulcer prevention from greater patient engagement by healthcare professionals.

    It concluded that the evidence was unclear about whether changes in clinical decision making from using SEM Scanner 200 reduce pressure ulcer incidence.

Research is needed on whether using preventive measures earlier affects pressure ulcer incidence

4.2 The clinical experts considered that SEM Scanner 200 provides information that could affect decisions about when to intensify preventive measures. These measures include improving the specification of the foam mattress, doing more regular repositioning of the patient, or other pressure-relieving measures. One clinical expert said that using SEM Scanner 200 allows nurses to intensify preventive measures earlier than when using clinical judgement alone. The committee acknowledged that using SEM Scanner 200 may result in preventive measures being introduced or intensified earlier. It noted that there was no evidence to show the effect of earlier interventions on pressure ulcer incidence. The committee concluded that research is needed to assess the effect of introducing preventive measures earlier on pressure ulcer incidence.

SEM Scanner 200 assesses the risk of pressure ulcers developing

4.3 The company explained that SEM Scanner is not intended to diagnose pressure ulcers but to diagnose the risk of pressure ulcers developing. Correspondence with the Medicines and Healthcare products Regulatory Agency confirmed that SEM Scanner 200 is used to identify patients at an increased clinical risk of pressure ulcers and should be seen as a diagnostic risk assessment tool.

Further research on using SEM Scanner 200 for pressure ulcer risk assessment is needed

4.4 The company acknowledged there is no appropriate reference standard for measuring subepidermal moisture and that this limited the assessment of diagnostic accuracy. The clinical experts also said that using visual skin assessment as a reference standard would confound the results. This was because SEM Scanner 200 is designed to assess the risk of pressure ulcers developing before any visible signs, such as redness, appear whereas visual skin assessment records visible pressure injuries. The committee concluded that further research is needed on the use of SEM Scanner 200 plus visual skin assessment compared with visual skin assessment alone for pressure ulcer risk assessment.

The evidence does not address how SEM Scanner 200 performs across different populations

4.5 The clinical experts explained that part of the visual skin assessment is to identify redness, which may not be visible in people with dark skin. Using a non-visual method such as SEM Scanner 200 for people with dark skin may offer advantages and could address an unmet need. The committee also considered that comorbidities and conditions associated with skin damage or swelling may influence subepidermal moisture levels and affect the clinical accuracy of SEM Scanner 200 to identify pressure ulcer risk. The committee concluded that further research should be done to assess the efficacy of SEM Scanner 200 in preventing pressure ulcers for patients with dark skin and for those with comorbidities.

Relevance to the NHS

There is NHS interest in SEM Scanner 200 because community and hospital-acquired pressure ulcers remain a significant problem

4.6 The NHS safety thermometer report states that from April 2014 to March 2015 approximately 25,000 patients developed new pressure ulcers. The proportion of people with a stage 2 to 4 pressure ulcer in the UK is estimated to be 5%. The clinical experts explained that, in view of the continued clinical challenges of preventing pressure ulcers in the community and in hospitals, there is increasing interest in using SEM Scanner 200 across the NHS.

Using devices for measuring subepidermal moisture is referenced in global clinical practice guidelines

4.7 The committee noted the recently updated US National Pressure Ulcer Advisory Panel (NPUAP), European Pressure Ulcer Advisory Panel (EPUAP) and Pan Pacific Pressure Injury Alliance (PPPIA) global clinical practice guideline in the treatment and prevention of pressure ulcers. This states that healthcare professionals should consider using a subepidermal or oedema measurement device in addition to routine visual skin assessment to assess the clinical risk of pressure ulcers. The committee also noted that, based on evidence, the guideline only proposed a weak positive recommendation for these devices when assessing risk in people with dark skin.

NHS considerations overview

SEM Scanner 200 provides an objective measure of pressure ulcer risk, which would be an advantage

4.8 SEM Scanner 200 provides an objective measure of variations in subepidermal moisture. Current risk assessment involves the combined use of validated scales and clinical judgement. The clinical experts explained that the availability of an accurate and objective measure of risk would be an advantage, particularly for training staff in pressure ulcer risk assessment.

The rationale for using SEM Scanner 200 needs further clinical testing

4.9 The company explained that the SEM Scanner 200 delta value reflects a measure of relative difference between the subepidermal moisture recorded over the bony prominences and surrounding tissues of the heels or sacrum. The greater the variation in subepidermal moisture (and therefore the delta value), the greater the likelihood of underlying localised inflammation. Although the committee accepted the rationale for this hypothesis, it considered that patients may have oedema from other causes and the hypothesis needs to be further tested in well-constructed clinical studies. It further noted that the interrater reliability of the device was reported by the company to be 83%. The committee concluded that further research would help to understand the reproducibility of the result.

SEM Scanner 200 needs cleaning between patients

4.10 The SEM Scanner 200 is classified as having a medium risk of cross-contamination. The company explained that cleaning has been shown to be effective in addressing the risk of cross-contamination. The clinical experts advised that cleansing wipes are used to clean SEM Scanner 200 and this is in keeping with NHS infection and control procedures. The company stated that there have been no reported cross-contamination adverse events with SEM Scanner 200.

SEM Scanner 200 has a battery life of 3 hours and a lifespan of over 3 years

4.11 The company explained that SEM Scanner 200 has a 3-year warranty but the battery life of the device may be longer than 3 years. The clinical experts advised that 3-hour battery capacity is adequate because SEM Scanner 200 is left on a charging station when not being used.


The company provides free training

4.12 The clinical experts explained that the company provides free training in the use of SEM Scanner 200. The device is easy to use, and the clinical experts described that staff became comfortable and familiar with its use within 2 weeks or so.

Cost modelling overview

Uncertainties about the clinical benefit of SEM Scanner 200 result in uncertain cost effectiveness

4.13 The committee noted that the key cost drivers, the reduction in pressure ulcer incidence and specificity of the device, were subject to considerable uncertainty. It concluded that more research was needed to establish the clinical and cost benefits of SEM Scanner 200.

Further research

Further research is needed to address the uncertainty about the efficacy of SEM Scanner 200 in reducing pressure ulcer incidence

4.14 The committee concluded that further research was needed to address uncertainties about the efficacy of SEM Scanner 200 in reducing pressure ulcer incidence. This research should investigate using SEM Scanner with visual skin assessment compared with standard risk assessment alone in judging the risk of pressure ulcers. It should control for the effect of increased engagement with healthcare professionals on pressure ulcer incidence. Pressure ulcers occur in acute and community care so research should address the effect of adopting the scanner in each of these settings independently. Additional research should specifically address the possible benefit of using the scanner in people with dark skin and those with a range of comorbidities known to influence fluid levels in the subepidermis and underlying tissues. Clinical studies using the scanner should be clear about how it affects clinical decision making; what effect it has on clinical outcomes and patient-related outcome measures; and the cost implications of its use.

  • National Institute for Health and Care Excellence (NICE)