Cerebral Palsy has several characteristics that can influence gross motor performance, the activities and participation of children and adolescents with this health condition. Knowing that family-centered assessment instruments are essential in the assessment of these patients, the Gross Motor Function – Family Report (GMF-FR) was developed, which is a self-reported instrument, easy to apply clinically and that assesses gross motor performance for this population.

Analyze GMF-FR measurement properties.

Methodological study. The GMF-FR was applied remotely with parents to validate measurement properties. The test-retest reliability was analyzed using the Intraclass Correlation Coefficient (ICC), for which a period of 7-30 days was respected: homogeneity by Cronbach's alpha. The discriminative validity between the GMF-FR and the Gross Motor Function Classification System (GMFCS) was observed by Spearman-rho correlation (rho) and One-way ANOVA, with post-hoc Tukey. A significance level of α=0.05 was considered.

146 children and adolescents with a mean age of 6.8 years (3,437) participated, covering all levels of functioning measured by the Gross Motor Function Classification System (GMFCS), with 50% level I, II and III and 50% level IV and V. Of these participants, 66.4% had bilateral impairment and 75.3% used some assistive technology. The GMF-FR was preferably answered by mothers (90.4%). Respondents had an average age of 37.3 years (SD=XX) and 52.7% had access to higher education. High homogeneity (α=0.99) and excellent reliability (ICC=0.99; 0.98≤95%CI≥0.99) were observed. The GMF-FR showed a strong negative correlation with the GMFCS (rho=-0.92p<0.001) and was able to discriminate gross motor performance between all GMFCS levels (Between Level I and II p<0.015; and between all other levels p<0.001).

The GMF-FR is a valid and reliable instrument to assess gross motor performance and capable of discriminating by level of GMFCS the children and adolescents with CP.

The GMF-FR is a new reliable instrument for assessing the gross motor performance of children and adolescents with CP, in addition to being accessible and easy to apply clinically, directly impacting the practice of health professionals during the assessment of key goals for treatment of children and adolescents with CP