Measurement of the perceived impact of sleep problems: the Spanish versionof the functional outcomes sleep questionnaire and the Epworth sleepiness scale

BACKGROUND: Excessive daytime sleepiness is a frequent symptom and a public health problem due to its association with automobile and work related acc idents. The aim of this study was to develop and carry out a preliminary as sessment of the Spanish version of the functional outcomes sleep questionna ire and the Epworth sleepiness scale, two instruments designed to evaluate patients with sleep disorders. MATERIAL AND METHODS: For the adaptation, the forward and back-translation method by bilinguals was used with professional and lay panel. Once tested for feasibility and comprehension, 39 patients with obstructive sleep apnea syndrome completed the Spanish version of the FOSQ and the Epworth sleepin ess scale, together with a question on self-rated health status. RESULTS: Difficulty of translation was assessed as low and the naturalness of Spanish expressions as high for all the items of the questionnaires exce pt for the response options of the Epworth sleepiness scale. Both questionn aires showed higher reliability than the standard proposed for individual c omparisons (Cronbach's alpha > 0.9). The FOSQ vigilance scale showed a high correlation with the Epworth score (r = -0.79), while for the other scales of the FOSQ correlations were moderate (r ranging from -0.52 to -0.68). Pa tients who reported "regular" or "poor" health had significantly worse scor es for most of the FOSQ scales. CONCLUSION: These results suggest that the Spanish versions of both questio nnaires are conceptually equivalent to the originals and that they show sim ilar characteristics of reliability and validity. The FOSQ vigilance scale assess daytime sleepiness similarly to Epworth but the others scales of the FOSQ provide additional information for these patients.