Translation, validity, and reliability of disability rating scale in Iranian patients with traumatic brain injury

Background: The Disability Rating Scale (DRS) is a short, efficient, and rapid instrument for assessing levels of functional disability, but little information is available on the translation and psychometric properties of its Persian version, especially for traumatic brain injury (TBI) patients. The aim of this study was to translate and adapt the Persian version of DRS and to determine the psychometric properties of the Persian version of this scale in patients with TBI. Materials and Methods: In this analytical cross-sectional study, 191 TBI patients (age range, 16–86 years) referred to the physiotherapy Center of PourSina Hospital in Rasht, Iran, were selected through census sampling. First, the DRS was translated into Persian, and then, the validity, reliability, and repeatability of DRS scores were evaluated. All patients were evaluated on admission and at discharge through the Glasgow Coma Scale (GCS) and Functional Independence Measure (FIM). Results: According to the reports of the translators, translation of the DRS into Persian language was easy. The quality of translation (including translation clarity, common language usage, conceptual equivalence, and overall quality of translation) was generally favorable. Inter-raters' reliability on admission and at discharge stages was excellent (intraclass correlation coefficient = 0.93–0.94). Cronbach's alpha values for the internal consistency of DRS on admission and at discharge stages were 0.96 and 0.97, respectively. The results showed a strong inverse relationship of DRS scores on admission and at discharge with GCS and FIM scores (in all cases more than 0.70, P < 0.0001). Conclusion: The validity, reliability, and repeatability of the DRS scores for the Persian version were confirmed. These results reflect that DRS can be used to determine the effects of therapeutic/rehabilitation interventions on levels of functional disability in Iranian patients with TBI.