O. Boccara

Background Low‐flow malformations (LFMs) are rare diseases with a significant impact on health‐related quality of life (HRQoL), especially in children. No disease‐specific questionnaire is available for children with LFMs. Objective To develop and validate a specific HRQoL questionnaire for children from 11 to 15 years old suffering from LFMs. Methods A preliminary questionnaire based on a verbatim from focus groups was created and sent to children from 11 to 15 years old suffering from LFMs, together with a dermatology‐specific and a generic HRQoL questionnaire (cDLQI and EQ‐5D‐Y). Results A total of 75 from 201 included children responded to the questionnaires. The final version of the questionnaire (cLFM‐QoL) included 15 questions and was not divisible into subscales. It demonstrated excellent internal consistency (cronbach 0.89), convergent validity and readability (SMOG 6.04). cLFM‐QoL mean score (± SD) was 12.9/45 (8.03) for all grades of severity, for mild 8.22/45 (7.5), moderate 14.03/45 (8.35), severe 12.35/45 (6.59) or very severe patients 20.7/45 (3.39) ( p 0 . 006 ). Conclusion cLFM‐QoL is a validated short and easy to use specific questionnaire with excellent psychometric capacities. It will be suitable for any children aged 11–15 with LFMs, in daily practice or clinical trials.