ORIGINAL ARTICLE Validation and modification of the Epworth Sleepiness Scale in Peruvian population Edmundo Rosales-Mayor & Jorge Rey de Castro & Leandro Huayanay & Kenny Zagaceta Received: 31 July 2010 / Revised: 10 January 2011 / Accepted: 13 January 2011 # Springer-Verlag 2011 Abstract Purpose The main purpose of this study was to develop a cross-cultural adaptation of the Epworth Sleepiness Scale for Peruvian population (ESS-VP) and to provide evidence of reliability and validity to this scale. We also modified the ESS-VP for non-driving Peruvian population (ESS-MPV). Methods Participants were Peruvians between 18 and 65 years. Five-phase design: Translation and retranslation of the original scale; comprehension evaluation (n =60); reliability or test–retest (n =75); internal consistency and construct validity (n =219); and change of sensibility (n = 36). Just as in the ESS-PV, the same procedure was applied to ESS-MPV except the first phase. Results The ESS-PV and ESS-MPV had an adequate comprehension. They were reliable over time (test–retest), being better within a period of 2 weeks. They also had adequate internal consistency (Cronbach's alpha: 0.790 and 0.789). Two factors were extracted in both scales, being only the first factor in which all items showed statistically significant loads. Both scales are sensitive to sleepiness change in patients with obstructive sleep apnea during treatment. Conclusions The ESS-VP and ESS-MPV, adapted to adult Peruvian population, are comparable to the original scale, reliable, valid, and change-sensitive. It is proposed that the ESS-MPV should be applied in Peruvian population who do not drive motorized vehicles Keywords Peru . Validation study . Epworth sleepiness scale . Sleepiness . Obstructive sleep apnea Introduction Studies in different countries have showed that sleepiness is a problem in about 0.3–25% of the population [1, 2]. These different prevalences are due to the differences in study population and in the definition of sleepiness used. There are a few studies conducted in Peru, which have reported values between 30–35% [3–5]. No comparisons are possible because these studies used different instru- ments to assess sleepiness. The Epworth Sleepiness Scale (ESS) [6] is used to assess sleepiness, is widely used worldwide, is easy to implement, cost-effective, and simple. The scale is potentially applica- ble to persons whose primary symptom is the tendency to fall asleep or sleepiness, such as those affected by the obstructive sleep apnea (OSA) [7] or narcolepsy [8]. But E. Rosales-Mayor : J. Rey de Castro : L. Huayanay : K. Zagaceta Facultad de Medicina, Universidad Peruana Cayetano Heredia, Lima, Peru E. Rosales-Mayor : J. Rey de Castro Centro de Trastornos Respiratorios del Sueño (CENTRES), Clínica Anglo Americana, Lima, Peru E. Rosales-Mayor : J. Rey de Castro : K. Zagaceta Grupo de Investigación en Sueño (GIS), Lima, Peru E. Rosales-Mayor (*) Hospital Clínic de Barcelona, Calle Villaroel 170, Barcelona 08036, Spain e-mail: erosales@clinic.ub.es E. Rosales-Mayor : J. Rey de Castro : L. Huayanay : K. Zagaceta Centro de Trastornos Respiratorios del Sueño (CENTRES), Clínica Anglo Americana, Av. Alfredo Salazar 314–Piso 10, San Isidro, Lima 27, Peru Sleep Breath DOI 10.1007/s11325-011-0485-1