Hammersmith functional rating scale for children with spinal muscular atrophy. Validation of the Spanish version

Aims. This study was conducted with the aim of developing the Spanish version of the Hammersmith functional rating scale for children with spinal muscular atrophy (SMA), to establish the interobserver reliability and to adapt it to Spanish children with SMA types II and III. Patients and methods. We assessed 31 children with a mean age of 4.7 years (range: 2.5-9 years) and they were reassessed at 3, 6 and 12 months. The children with SMA type II could not walk and the children with SMA type Ill were able to walk. Results. Interobserver reliability was 95%. The median of the score in the group with SMA type II was 17 (range: 0-34) and in the SMA type III group it was 39 (range: 37-40). The results of the group with SMA type II at 12 months were poorer, although not to a statistically significant extent, which suggested that the disease was getting worse. Conclusions. The Spanish version presents a high degree of interobserver reliability, is easy to administer in clinical practice and is a good tool for assessing the severity of the disease in patients with SMA, above all in those who are unable to walk.