Prevalence of isolated RBD in the city of Catania, Italy: a population-based study

Study Objectives: Few studies have analyzed the prevalence of isolated rapid eye movement sleep behavior disorder (RBD) giving different estimates. Aim of the study was to estimate the prevalence of isolated RBD in the city of Catania. Methods: A 3-stage design was adopted. Participants attending the offices of general practitioners in the city of Catania were screened with the RBD Single Question Screen questionnaire (Stage I). Positive participants were interviewed by phone and, if suspected of RBD, were invited for clinical examination by a movement disorders specialist and a sleep specialist (Stage II). After the clinical examination, patients diagnosed as probable isolated RBD (pRBD) were invited to undergo a video polysomnography (Stage III) to confirm the diagnosis of definite RBD. Results: A total of 1,524 participants were screened. Of these, 220 (14.4%) screened positive. One hundred forty-three of them were further screened by phone, of whom 75 were suspected RBD. Thirty-six patients were diagnosed as pRBD, giving a prevalence of 2.36% (95% confidence interval, 1.71-325). Twelve pRBD agreed to a video polysomnography and, of these, 4 were diagnosed as definite RBD, giving a prevalence of 0.26% (95% confidence interval, 0.07-0.67). Prevalence adjusted by nonparticipants was 3.48% (95% confidence interval, 2.67-4.52) and 1.18% (95% confidence interval, 0.45-1.37) for pRBD and definite RBD, respectively. Conclusions: Prevalence of both pRBD and definite RBD in Italy is comparable to the estimates reported in literature, confirming that isolated RBD has a low prevalence in the general population.