Cross-cultural adaptation and psychometric properties of the Kessler Scale of Psychological Distress to a traumatic brain injury population in Swahili and the Tanzanian Setting

Abstract Background To evaluate the psychometric properties of a Swahili version of the Kessler Psychological Distress scale in an injury population in Tanzania. Methods Swahili version of the Kessler Psychological Distress scale was developed by translation and back-translation by a panel of native speakers of both English and Swahili. The translated instruments were administered to a sample of Tanzanian adults from a traumatic brain injury registry. The content validity, construct validity, reliability, internal structure, and external reliability were analyzed using standard statistical methods. Results Both translated versions of the Kessler Psychological Distress scale were found to be reliable (>0.85) for all tested versions. Confirmatory factor analysis of one and two factor solution showed adequate results. Kessler Psychological Distress scale scores were strongly correlated to depression and quality of life (R>0.50). Conclusions This paper presents the first Swahili adaptations of the Kessler Psychological Distress scale as well as the first validation of these questionnaires in Tanzania. The instrument was found to have acceptable psychometric properties, resulting in a new useful tool for medical and social research in this setting