Background: Epworth sleepiness scale (ESS) has been used widely in the assessment of daytime sleepiness for research and clinical purposes. Hence, this study was done to translate the ESS in Tamil and to assess the construct validity and reliability of the Tamil version among adolescents in rural Puducherry, South India.
Materials and methods: Translation of the ESS by native language experts and pilot tested with subsample of adolescents. Final Tamil version was administered among 789 Tamil-speaking adolescents in the selected villages of rural Puducherry (union territory in South India). Construct validity was assessed by exploratory factor analysis through principal component method. Confirmatory factor analysis was done to obtain the goodness-of-fit. Reliability of questionnaire was assessed through Cronbach's alpha coefficient.
Results: Two factor structures were obtained with Eigenvalues of 3.49 and 1.09, respectively. Both factors accounted for about 57.4% of the variance. Two-factor model assessed by confirmatory factor method found Chi-square value of 215.57 (P < 0.001). Goodness-of-fit revealed acceptable comparative fit indices (0.91). The reliability coefficient (Cronbach's alpha) for complete ESS was 0.81. Factor-based analysis showed that the Cronbach's reliability coefficient was 0.83 and 0.75 for the first and second factor, respectively.
Conclusion: Our study concludes that the ESS questionnaire is internally valid and consistent with good reliability coefficient for application in Tamil-speaking rural adolescents. However, further research can be done to content validate the questionnaire with standard diagnostic tool.
Keywords: Adolescent; disorders of excessive somnolence; sleep; validation studies.