Technical and clinical performance of the thermo‐test device “Q‐Sense” to assess small fibre function: A head‐to‐head comparison with the “Thermal Sensory Analyzer” TSA in diabetic patients and healthy volunteers

Abstract

Background Thermo‐test devices are rarely used outside specialized pain centres because of high acquisition costs. Recently, a new, portable device (“Q‐Sense”) was introduced, which is less expensive but has reduced cooling capacity (20°C). We assessed the reliability/validity of the “Q‐Sense” by comparing it with the Thermal Sensory Analyzer (TSA). Methods Using a phantom‐skin model, the physical characteristics of both devices were compared. The clinical performance was assessed in a multicentre study by performing Quantitative Sensory Testing (QST) in 121 healthy volunteers and 83 diabetic patients (Eudra‐Med‐No. CIV‐12‐05‐006501). Results Both device types showed ~40% slower temperature ramps for heating/cooling than nominal data. Cold/warm detection thresholds (CDT, WDT) and heat pain thresholds (HPT) of healthy subjects did not differ between device types. Cold pain thresholds (CPT) were biased for Q‐Sense by a floor effect (p < .001). According to intraclass correlation coefficients (ICC), agreement between TSA and Q‐Sense was good/excellent for CDT (ICC = 0.894) and WDT (ICC = 0.898), moderate for HPT (ICC = 0.525) and poor for CPT (ICC = 0.305). In diabetic patients, the sensitivity of Q‐Sense to detect cold hypoesthesia was reduced in males >60 years. Moderate correlations between thermal detection thresholds and morphological data from skin biopsies (n = 51) were similar for both devices. Conclusions Physical characteristics of both thermo‐test devices are similarly limited by the poor temperature conduction of the skin. The Q‐Sense is useful for thermal detection thresholds but of limited use for pain thresholds. For full clinical use, the lower cut‐off temperature should be set to ≤18°C. Significance High purchase costs prevent a widespread use of thermo‐test devices for diagnosing small fibre neuropathy. The air‐cooled “Q‐Sense” could be a lower cost alternative, but its technical/clinical performance needs to be assessed because of its restricted cut‐off for cooling (20°C). This study provides critical information on the physical characteristics and the clinical validity/reliability of the Q‐Sense compared to the “Thermal Sensory Analyzer” (TSA). We recommend lowering the cut‐off value of the Q‐Sense to ≤18°C for its full clinical use.

Small Fiber Neuropathy in Diabetes Polyneuropathy: Is It Time to Change?

“…This may explain why QST techniques demonstrate a modest correlation with IEFND. 27 Newer updates like the Medoc TSA-II have been able to mitigate some of these limitations; however, the psychophysical aspect of the tests is a non-modifiable limitation. Furthermore, there are very limited data on whether QSTs are able to detect small to modest degrees of improvement in SFF, a crucial aspect for suitability of technique for use in neuropathy intervention trials.…”

Diabetes Distal Peripheral Neuropathy: Subtypes and Diagnostic and Screening Technologies

“…70 Since 2015, the literature search identified thirteen studies comparing, for instance, different QST devices and evaluating new methodologies or technological approaches (see Table 3). [71][72][73][74][75][76][77][78][79][80][81][82][83] NerveCheck (Phi Med Europe SL, Barcelona, Spain), in particular, reveals technological advancement of traditional QST. NerveCheck is a small, portable device, and yields rapid results.…”

The Role of Quantitative Sensory Testing in Clinical Medicine and Research

“…Abnormal thermal QST may be the first and only indication of subclinical neuropathy [28,29]. Thermal QST has been shown to correlate with or be of greater sensitivity than skin biopsy IENFD [23,30].…”