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

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 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.