Rasch-Transformed Total Neuropathy Score clinical version (RT-TNSc^©) in patients with chemotherapy-induced peripheral neuropathy

Composite scales such as the Total Neuropathy Score clinical version (TNSc^©) have been widely used to measure neurological impairment in a standardized manner but they have been criticized due to their ordinal setting having no fixed unit. This study aims to improve impairment assessment in patients with chemotherapy-induced peripheral neuropathy (CIPN) by subjecting TNSc^© records to Rasch analyses. In particular, we wanted to investigate the influence of factors affecting the use of the TNSc^© in clinical practice. TNSc^© has 7 domains (sensory, motor, autonomic, pin-prick, vibration, strength, and deep tendon reflexes [DTR]) each being scored 0-4. Data obtained in 281 patients with stable CIPN were subjected to Rasch analyses to determine the fit to the model. The TNSc^© did not meet Rasch model's expectations primarily because of misfit statistics in autonomic and DTR domains. Removing these two, acceptable model fit and uni-dimensionality were obtained. However, disordered thresholds (vibration and strength) and item bias (mainly cultural) were still seen, but these findings were kept to balance the assessment range of the Rasch-Transformed TNSc^© (RT-TNSc^©). Acceptable reliability findings were also obtained. A 5-domains RT-TNSc^© may be a more proper assessment tool in patients with CIPN. Future studies are needed to examine its responsive properties.