Quality of life in neurofibromatosis 1: development and validation of a tool dedicated to cutaneous neurofibromas in adults

BACKGROUND

Cutaneous neurofibromas (cNF), present in 95% of individuals with neurofibromatosis 1 (NF1), are considered as one of the greatest medical burden because of physical disfigurement. No specific score evaluates their impact on quality of life (QoL).

OBJECTIVE

To develop a specific score assessing cNF-related QoL.

METHODS

Through a multidisciplinary workshop including 10 patients, 3 expert-in-NF1 physicians, 3 health care workers (nurses and psychologist) and 1 methodologist, the French version of the Skindex-16 was modified by adding 3 items. The new cNF-Skindex was validated among patients with NF1 recruited in the ComPaRe online cohort, in France (N=284). Construct validity was assessed by comparing it with the EQ-5D-5L, its visual analog scale and the MYMOP2 and by assessing its association with patients' characteristics. Reliability was assessed by a test-retest. An English version of the tool was developed using a back forward translation.

RESULTS

A total of 228 individuals with NF1, with cNF answered the 19-item questionnaire. These items fitted into 3 domains: emotions, symptoms, functioning. One was dropped during analysis because >90% responders were not concerned. The cNF-Skindex significantly correlated with the EQ-5D-5L (N=193) and MYMOP2 (N=210) indicating good external validity: rs 0.38 (p<0.001), and 0.58 (p<0.001) respectively. Having >50 cNF was the only independent variable associated with the total score cNF-Skindex (β=15.88, 95%CI 6.96 - 24.81, p=0.001), and with the 3 sub-scores: "functioning" (β=2.65, 95%CI 0.71 - 4.59, p=0.008), "emotions" (β=17.03, 95%CI 4.11 - 29.96, p=0.010) and "symptoms" (β=3.90, 95%CI 1.95 - 5.85, p<0.001). Test-retest reliability (N=133) found an ICC at 0.96 demonstrating good reproducibility.

CONCLUSION

The cNF-Skindex demonstrated excellent psychometric properties. The global and sub-scores were increased with higher number of cNF arguing for its use in further trials aiming to reduce their number or prevent their development. Cross-cultural validation and evaluation of its responsiveness are the next steps.