Evaluation of the Spanish version of the DASH and carpal tunnel syndrome health-related quality-of-life instruments: cross-cultural adaptation process and reliability

The methodologic requirements for cross-national use of specific health outcome instruments in hand surgery are presented. The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire as a specific upper-extremity instrument and the Carpal Tunnel Syndrome (CTS) questionnaire as a specific disease instrument were adapted to Spanish for use in international studies. The adaptations were based on translation/back translation methodology. Meetings of translators, researchers, and patients were organized to produce successive versions. A study involving 50 people was carried out to consider the relative value (through a visual analog scale) of each response choice of the questionnaire items. Internal consistency and reproducibility of the Spanish version of both instruments were assessed by self-administering the questionnaires to 42 patients with the diagnosis of CTS on 2 different occasions 1 week apart. The average ratings of equivalence of the translated version with the original were high, regardless of the difficulty of translation. The adaptation process of the DASH and CTS instruments concluded with questionnaires conceptually equivalent to the original and with an acceptable level of reliability.