Guidance
4 NHS considerations
System impact
4.1 A claimed benefit of VibraTip is the reduced variability in results of diabetic peripheral neuropathy testing compared with the 10 g monofilament and the 128 Hz tuning fork. The Bracewell et al. (2012) study reported intra‑rater reliability results for use of VibraTip in a small high risk patient population (n=18). An expert adviser reported that he is involved in a study of the accuracy of the use of VibraTip amongst different healthcare professionals in primary and secondary care.
4.2 The sponsor has claimed that little user training is needed with VibraTip. During the selection and routing of VibraTip, the Committee obtained expert advice that agreed that only minimal training would be needed, but there was no published evidence to support this.
4.3 The External Assessment Centre highlighted that the battery life of VibraTip has implications for the cost modelling. The Horsfield and Levy (2013) study was a technical assessment of 3 different activation patterns of VibraTip and the influence of these on battery life and the consistency of the stimulus. Results from a pattern designed to mimic use in clinical practice, showed that the amplitude reduced to 64% of its initial value after 3500 activations, but the frequency only reduced to 94%. The authors concluded that each VibraTip could test at least 100 patients. The External Assessment Centre considered that there is some uncertainty about the estimate of 100 patients because the duration of each activation in the study was 0.5 seconds instead of the 1 second duration recommended in the VibraTip Instruction for Use. The External Assessment Centre concluded that poor repeatability of the stimulus due to reductions in the amplitude over time is an important limitation to the clinical repeatability of the test, and the effect of these reductions in amplitude on diagnostic accuracy are unknown.
Committee considerations
4.4 The Committee noted that detection, diagnosis and management of diabetic peripheral neuropathy is a very important clinical area which has the potential to affect millions of people in the UK, and that small improvements in the timing and rate of diabetic peripheral neuropathy detection have the potential to impact substantially on clinical costs.
4.5 The Committee considered that important aspects of the system benefits concerned the useable lifetime of both VibraTip and the 10 g monofilament, as well as the 'real world' availability of tuning forks in clinical settings, and the variability of tuning fork usage in clinical practice. Expert opinion and existing evidence provided limited information on these issues. The Committee noted there remained uncertainty and considered it important that these aspects be included in further research so that the clinical and economic implications could be assessed.
4.6 The Committee considered that credible evidence was presented by expert advisers that VibraTip was both easier to learn to use and to use, but there was limited clinical evidence to support these statements. The Committee discussed the time taken to do a test with VibraTip compared with the tuning fork and decided it was unclear that there would be significant time savings when using VibraTip.
4.7 The Committee considered that the technical evidence supporting the improved consistency of VibraTip compared with the calibrated tuning fork in the diagnosis of diabetic peripheral neuropathy was plausible, but that it was of low quality. It understood that there were uncertainties about the possibility of false negative results towards the end of the battery life of the device. The Committee decided that a high quality diagnostic accuracy study could resolve these issues.