ABSTRACT
INTRODUCTION: Restless legs syndrome (RLS) is etiologically divided into primary and secondary syndromes. However, a comparative description of both types is lacking in the literature. We compared primary and secondary RLS with respect to demographic determinants, associated risk factors, and comorbidities. METHODS: Following a cross-sectional survey on the prevalence of RLS in a Saudi population, RLS cases were identified using the International RLS Study Group (IRLSSG) criteria. Cases were assessed with an interview-based questionnaire regarding baseline characteristics, risk factors, and comorbidities and with lower limb examinations and laboratory measurements. RLS severity was assessed using the IRLSSG Severity Rating Scale. RESULTS: In total, 78 patients with RLS, including 50 (64.1%) primary and 28 (35.9%) secondary cases, were examined. Of the primary cases, 35 (70%) were male; of the secondary cases, 25 (89.3%) were female (P < 0.001). Multivariate regression confirmed the association of male gender with primary RLS (odds ratio = 14.53, 95% confidence interval [2.9-75], P = 0.001). There were more dark- and black-skinned participants in the primary RLS group (38, 72%) than in the secondary group (15, 28%) (P = 0.042). Iron deficiency was observed in most (26, 92%) of the secondary cases. More severe symptoms were reported in secondary than in primary RLS cases (P < 0.05). CONCLUSIONS: Primary RLS is more common but less severe than secondary RLS. Male gender and ethnicity play significant roles in primary RLS, whereas female gender and iron deficiency may be the main risk factors associated with secondary RLS.
ABSTRACT
STUDY OBJECTIVES: The pathophysiology of restless legs syndrome (RLS) may be related to abnormalities in central dopamine pathways. Vitamin D may play a role in the pathophysiology of RLS by modulating the dopaminergic system. The aim of our study is to examine the possible link between RLS and vitamin D deficiency. METHODS: The total number of subjects enrolled was 201, including 78 patients with RLS based on the International RLS Study Group (IRLSSG) diagnostic criteria and 123 controls. Serum 25-hydroxy vitamin D levels were measured in both groups. RLS severity was assessed in all cases using the IRLSSG symptom severity rating scale. RESULTS: Fifty-nine patients with RLS (75.6%) and 52 controls (42.3%) had a diagnosis of vitamin D deficiency, P < .001. The odds ratio (OR) of the development of RLS was 4.24 for those with a vitamin D level < 50 nmol/L compared to those with a vitamin D level ≥ 50 nmol/L (P < .001, 95% confidence interval [CI] 2.3-7.9). After adjusting for all other significant factors in the multivariate logistic model, vitamin D was significantly associated with RLS (OR 3.1, P < .002, 95% CI 1.51-6.38). Moreover, a dark or black skin color (OR 3.4, P < .001, 95% CI 1.5-6.3) and working as a teacher (OR 8.8, P < .001, 95% CI 3.4-23.5) were also independently significantly associated with RLS. CONCLUSIONS: Our study identified an association between vitamin D deficiency and RLS. Consequently, vitamin D deficiency should be considered in the management of RLS. However, further studies are needed to evaluate the causality relationship between vitamin D level and RLS.
