Development of patient reported outcome measures assessing tumor pain intensity and tumor pain interference for individuals with neurofibromatosis type 1 and plexiform neurofibromas: qualitative findings.

BACKGROUND

Pain is a common symptom in individuals with neurofibromatosis type 1 (NF1) that often is associated with plexiform neurofibroma (pNF) tumors. To date, no patient-reported outcome measures have been validated specifically to assess pNF-related pain intensity or pain interference in this population. Such measures are sorely needed since pain is being considered as an outcome in clinical trials targeting reduction of pNF. The study aims were to: (1) obtain qualitative information from individuals with NF1 and pNFs about their pain and its measurement and (2) modify existing scales to assess pNF-related pain intensity and pain interference for NF1 clinical trials.

METHODS

For this multi-site, qualitative study, 56 individuals (26 children, 6-16 years; 30 adults, 18-68 years) with NF1 and pNF participated in a focus group and/or individual interview about pain intensity and pain interference (concept elicitation) and also provided feedback about existing pain measures (Numeric Rating Scale-11 and Pain Interference Index) assessing these domains (cognitive debriefing). Four additional waves of cognitive debriefing interviews further refined the measures. Qualitative concept elicitation data from transcripts were coded, analyzed using NVivo software, and thematic analysis was conducted using both deductive and inductive techniques. Additional themes and systematic problems and suggestions regarding the measures were gleaned from reviewing the field notes and interview transcriptions generated by the cognitive debriefing sessions.

RESULTS

Concept elicitation themes included descriptions of two types of pNF-related pain (chronic and episodic), variability of pain over time, varying ability to recall pain, lack of knowledge of pNFs, and the ways pain interferes with daily activities. Cognitive debriefing themes included information on how to rate pNF-related pain intensity apart from other pain; problems and suggestions regarding the measures included difficulty comprehending some items and preferences for alternative wording and formatting. Based on these qualitative results, the measures' instructions, items, and formatting were modified to create the PAin INtensity Scale for plexiform neurofibromas (PAINS-pNF) and the Pain Interference Index for plexiform neurofibromas (PII-pNF) for administration on a mobile app or web-based platform.

CONCLUSIONS

The PAINS-pNF and PII-pNF are promising self-report measures developed using patient engagement to evaluate tumor pain intensity and pain interference in NF1 clinical trials. The second phase of the study to provide reliability, validity, and normative data for individuals with NF1 and pNFs ages 8 years and older is underway.