Functional assessment for people unable to walk due to spinal muscular atrophy and Duchenne muscular dystrophy. Translation and validation of the Egen Klassifikation 2 scale for the Spanish population

The Egen Klassifikation 2 Scale (EK2), expansion of the EK scale, assesses the functional capacity of people with spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) that are in wheelchair phase. This version is more specific for SMA than its EK predecessor. To examine the validity and reliability of the Spanish version of the scale as a tool for measuring the functional capacity in patients with DMD and SMA who are in wheelchairs. First, a translation-back-translation into Spanish of the English version of the EK2 was performed; later, we studied the reliability of the translated version. For this, 39 patients, aged between 4 and 60, who were evaluated by two observers, were recruited. To evaluate the intra-observer consistency, two assessments by the same observer were performed, and the inter-observer third assessment was performed by a second observer. The obtained values based on the total score of the scale items (sum EK2) reflect excellent intra- and inter-observer reliability, 0.993 and 0.988 respectively. Also, for each of the items, reliability was excellent except for one item in which it was good. The Spanish version of the EK2 scale is a valid and reliable instrument for the Spanish population as a tool for measuring the functional capacity in patients with SMA and DMD who are in wheelchairs.