Development and pilot validation of a novel disfigurement severity scale for plexiform neurofibromas in children with neurofibromatosis type 1.

Background/aims: We developed an observer disfigurement severity scale for neurofibroma-related plexiform neurofibromas to assess change in plexiform neurofibroma-related disfigurement and evaluated its feasibility, reliability, and validity.
Methods: Twenty-eight raters, divided into four cohorts based on neurofibromatosis type 1 familiarity and clinical experience, were shown photographs of children in a clinical trial (NCT01362803) at baseline and 1 year on selumetinib treatment for plexiform neurofibromas ( n  = 20) and of untreated participants with plexiform neurofibromas ( n  = 4). Raters, blinded to treatment and timepoint, completed the 0-10 disfigurement severity score for plexiform neurofibroma on each image (0 = not at all disfigured, 10 = very disfigured). Raters evaluated the ease of completing the scale, and a subset repeated the procedure to assess intra-rater reliability.
Results: Mean baseline disfigurement severity score for plexiform neurofibroma ratings were similar for the selumetinib group (6.23) and controls (6.38). Mean paired differences between pre- and on-treatment ratings was -1.01 (less disfigurement) in the selumetinib group and 0.09 in the control ( p  = 0.005). For the disfigurement severity score for plexiform neurofibroma ratings, there was moderate-to-substantial agreement within rater cohorts (weighted kappa range = 0.46-0.66) and agreement between scores of the same raters at repeat sessions ( p  > 0.05). In the selumetinib group, change in disfigurement severity score for plexiform neurofibroma ratings was moderately correlated with change in plexiform neurofibroma volume with treatment ( r  = 0.60).
Conclusion: This study demonstrates that our observer-rated disfigurement severity score for plexiform neurofibroma was feasible, reliable, and documented improvement in disfigurement in participants with plexiform neurofibroma shrinkage. Prospective studies in larger samples are needed to validate this scale further.
Competing Interests: Declaration of conflicting interestsDr B.C.W. and Dr A.M.G. have unpaid advisory roles for AstraZeneca and SpringWorks. Dr M.J.F. has paid advisory roles for AstraZeneca and SpringWorks and research support from AstraZeneca, Array BioPharma, and Exelixis for plexiform neurofibroma clinical trials. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. Dr M. B. has a paid advisory role on the external advisory board for the Koselugo Registry through Alexion.