Evaluating the Content Validity of the Modified Neuropathy Total Symptom Score-6 Self-Administered (mNTSS-6-SA) in a Painful Diabetic Peripheral Neuropathy Population.

Introduction: People with diabetes often develop painful diabetic peripheral neuropathy (pDPN). Symptoms of pDPN vary and often lead to impairments in basic daily activities and negative impacts on quality of life. The Neuropathy Total Symptom Score-6 (NTSS-6) assesses the frequency and intensity of six neuropathic sensory symptoms. Validity of the NTSS-6 for neuropathic populations has been evaluated for a 24-hour clinician-reported version and 4-week self-administered (SA) version. The aim of this study was to evaluate the content validity of the Neuropathy Total Symptom Score-6 self-administered (NTSS-6-SA) modified for use with a 7-day recall period in a sample of people with pDPN. Methods: This was an observational qualitative study consisting of concept elicitation and cognitive debriefing interviews. The study included 25 US-based, English-speaking adults who had a physician-confirmed diagnosis of DPN and who self-reported moderate-to-severe pain in their feet or legs. Participants were asked to describe their experiences with pDPN and to review the NTSS-6-SA with a 7-day recall period. Based on findings from the first 13 interviews (Wave 1), the NTSS-6-SA was modified to address minor comprehension problems and incorporate patient feedback. The modified NTSS-6-SA (mNTSS-6-SA) was then reviewed in 11 interviews (Wave 2). Results: The measure was interpreted as intended, well-understood, and included content relevant to the experiences that study participants found important. Conclusion: The evidence from this study supported the content validity of the mNTSS-6-SA for the pDPN population.