Brazilian version of the CHOP INTEND scale: cross-cultural adaptation and validation

Background Spinal muscular atrophy (SMA) is a rare genetic disease that causes progressive muscle weakness and impacts motor function. The type I is the most severe presentation and affects infants before 6 months old. In addition, the instruments available for assessing motor function have limitations when applied to infants with neuromuscular diseases and significant muscle weakness. Objective To translate, cross-culturally adapt, and validate the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) to Brazilian Portuguese. Methods The present study comprised the translation, synthesis of translations, backtranslation, consolidation by a committee of experts, and test of the final version of the CHOP INTEND in 13 patients with SMA type I. We also assessed the content validity and reliability of the translated version. Results The scale was translated considering semantic, structural, idiomatic, and cultural aspects. All agreement rates were > 0.8, the overall content validity index of the instrument was 0.98, and inter-rater reliability using the intraclass correlation coefficient was 0.998. Conclusion The Brazilian version of the CHOP INTEND met semantic and technical equivalence criteria with the original version and was valid and reliable for patients with SMA type I.