title: Construct validity and factor structure of the pittsburgh sleep quality index and epworth sleepiness scale in a multi-national study of African, South East Asian and South American college students.
abstract: BACKGROUND
  The Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS) are questionnaires used to assess sleep quality and excessive daytime sleepiness in clinical and population-based studies. The present study aimed to evaluate the construct validity and factor structure of the PSQI and ESS questionnaires among young adults in four countries (Chile, Ethiopia, Peru and Thailand).
  
  
  METHODS
  A cross-sectional study was conducted among 8,481 undergraduate students. Students were invited to complete a self-administered questionnaire that collected information about lifestyle, demographic, and sleep characteristics. In each country, the construct validity and factorial structures of PSQI and ESS questionnaires were tested through exploratory and confirmatory factor analyses (EFA and CFA).
  
  
  RESULTS
  The largest component-total correlation coefficient for sleep quality as assessed using PSQI was noted in Chile (r = 0.71) while the smallest component-total correlation coefficient was noted for sleep medication use in Peru (r = 0.28). The largest component-total correlation coefficient for excessive daytime sleepiness as assessed using ESS was found for item 1 (sitting/reading) in Chile (r = 0.65) while the lowest item-total correlation was observed for item 6 (sitting and talking to someone) in Thailand (r = 0.35). Using both EFA and CFA a two-factor model was found for PSQI questionnaire in Chile, Ethiopia and Thailand while a three-factor model was found for Peru. For the ESS questionnaire, we noted two factors for all four countries.
  
  
  CONCLUSIONS
  Overall, we documented cross-cultural comparability of sleep quality and excessive daytime sleepiness measures using the PSQI and ESS questionnaires among Asian, South American and African young adults. Although both the PSQI and ESS were originally developed as single-factor questionnaires, the results of our EFA and CFA revealed the multi- dimensionality of the scales suggesting limited usefulness of the global PSQI and ESS scores to assess sleep quality and excessive daytime sleepiness.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States of America.
authors.forename: Bizu
authors.initials: B
authors.lastname: Gelaye
authors.affiliation: Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Vitool
authors.initials: V
authors.lastname: Lohsoonthorn
authors.affiliation: Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; College of Public Health Sciences, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Somrat
authors.initials: S
authors.lastname: Lertmeharit
authors.affiliation: School of Nursing, Walailak University, Nakhon Si Thammarat, Thailand.
authors.forename: Wipawan C
authors.initials: WC
authors.lastname: Pensuksan
authors.affiliation: Universidad San Martin de Porres, Lima, Peru.
authors.forename: Sixto E
authors.initials: SE
authors.lastname: Sanchez
authors.affiliation: Addis Continental Institute of Public Health, Addis Ababa, Ethiopia.
authors.forename: Seblewengel
authors.initials: S
authors.lastname: Lemma
authors.affiliation: Addis Continental Institute of Public Health, Addis Ababa, Ethiopia.
authors.forename: Yemane
authors.initials: Y
authors.lastname: Berhane
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States of America.
authors.forename: Xiaotong
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Centro de Rehabilitación Club de Leones Cruz del Sur, Punta Arenas, Chile.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Vélez
authors.affiliation: Centro de Rehabilitación Club de Leones Cruz del Sur, Punta Arenas, Chile.
authors.forename: Clarita
authors.initials: C
authors.lastname: Barbosa
authors.affiliation: Centro de Rehabilitación Club de Leones Cruz del Sur, Punta Arenas, Chile.
authors.forename: Asterio
authors.initials: A
authors.lastname: Anderade
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States of America; Department of Mathematics & Statistics, Georgetown University, Washington, DC, United States of America.
authors.forename: Mahlet G
authors.initials: MG
authors.lastname: Tadesse
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States of America.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
mesh_terms: D000328:Adult; D002677:Chile; D003430:Cross-Sectional Studies; D005002:Ethiopia; D005260:Female; D006801:Humans; D008297:Male; D010568:Peru; D012890:Sleep; D012893:Sleep Wake Disorders / Q000175:diagnosis; D011795:Surveys and Questionnaires; D013785:Thailand