Incidence of restless legs syndrome in two population-based cohort studies in Germany

Objectives: Prospective data about the new-onset of restless legs syndrome (RLS) are lacking. Our aim was to assess the incidence rate of RLS in the general population. Methods: RLS, defined by the minimal diagnostic criteria, was assessed twice in two independently conducted prospective population-based cohort studies in Germany. The Dortmund Health Study (DHS) had a mean follow-up of 2.2 years, and included 1312 participants, and the Study of Health in Pomerania (SHIP) followed 4308 participants for, on average, 5.2 years. RLS was assessed during face-to-face interviews in both studies at baseline and at follow-up in SHIP, and with mailed questionnaires at follow-up in DHS. Results: The age-standardized incidence rate of RLS was 22/1000 person-years (p-y) (cumulative incidence over the follow-up: 9.1%) in DHS and 9/1000 p-y (cumulative incidence: 7.0%) in SHIP. Women had a higher incidence rate than men (DHS: 27/1000 p-y vs. 17/1000 p-y, p = 0.28; SHIP: 12/1000 p-y vs. 7/1000 p-y, p < 0.001). There was a linear increase in RLS incidence rate with age in both studies. The persistence of RLS symptoms from baseline to follow-up was 47.4% in DHS and 41.5% in SHIP. Conclusion: The incidence rate of RLS is high, while the persistence of RLS over time is low, suggesting that RLS symptoms vary considerably. The increased RLS incidence rate among women and the elderly is consistent with previous prevalence data. (C) 2011 Elsevier B.V. All rights reserved.