Diagnostic accuracy and operational feasibility of the MESI mTABLET in secondary-care diabetic foot clinics: a pilot cross-sectional service evaluation.

INTRODUCTION: Peripheral arterial disease (PAD) is a common and serious complication in people with diabetes, particularly those with diabetic foot disease. Although measurement of the ankle-brachial pressure index (ABPI) and/or toe-brachial pressure index (TBPI) are first-line investigations for PAD, they are time-consuming and require training. Automated devices such as the MESI mTABLET may overcome these barriers, but diagnostic accuracy in diabetic populations is limited. METHODS: We conducted a cross-sectional diagnostic accuracy study in patients attending joint vascular and podiatry diabetic foot clinics at a UK tertiary centre. Participants requiring ABPI assessment were considered for inclusion. Manual ABPI/TBPI measurements were obtained according to guidelines and served as the reference standard. Automated measurements were taken using the MESI mTABLET. PAD was defined as an ABPI <0.9 or TBPI <0.7. Diagnostic accuracy was assessed via Spearman correlation, sensitivity, specificity, predictive values, and area under the receiver operating characteristic (AUROC) curve. Patients were also stratified using the WIfI (Wound, Ischaemia, foot Infection) classification. RESULTS: A total of 102 limbs from 62 patients were assessed. Device failure occurred in 20 limbs, resulting in a total of 82 limbs for analysis. MESI-derived ABPI and TBPI showed strong correlation with manual measurements (ρ = 0.850, p < 0.001 and ρ = 0.823, p < 0.001, respectively). The mean manual values were 0.96 (SD = 0.24) and 0.67 (SD = 0.27) for ABPI and TBPI, respectively, compared with 1.10 (SD = 0.20) and 0.83 (SD = 0.30) for the MESI device. At standard diagnostic thresholds, MESI ABPI had a sensitivity of 70% and specificity of 79%, while MESI TBPI had a sensitivity of 64% and specificity of 92%. The AUROC was 0.971 for ABPI and 0.915 for TBPI. MESI measurements were significantly quicker to obtain than the manual measurements (394 s vs 1139 s, p < 0.001). CONCLUSION: The MESI mTABLET demonstrates favourable diagnostic performance and substantial time-saving in this cohort. However, it overestimates ABPI/TBPI values and alternative cut-offs may be necessary to maximise sensitivity and specificity.