This study aimed to investigate the potential association between Restless Legs Syndrome (RLS) and Overactive Bladder (OAB). The hypothesis was that individuals diagnosed with RLS would exhibit a higher prevalence of OAB symptoms compared to the general population, suggesting a possible shared underlying pathophysiology or related symptomatic manifestation. The study further aimed to characterize the specific urinary symptoms reported by RLS patients and to explore the influence of age on the co-occurrence and severity of both conditions.

This cross-sectional study recruited 135 patients diagnosed with RLS based on the Persian version of the Cambridge-Hopkins RLS diagnostic questionnaire (CHRLSq). Participants provided informed consent and completed the International Consultation on Incontinence Questionnaire Overactive Bladder Module (ICIQ-OAB) to assess the presence and severity of OAB symptoms, including urinary frequency, nocturia, urgency, and urgency urinary incontinence (UUI). Demographic data, including age and gender, as well as information on pre-existing medical conditions and medication use, were collected. Statistical analysis was performed using SPSS software (version 23). The Kolmogorov-Smirnov test assessed data normality. Descriptive statistics summarized the prevalence of RLS and OAB symptoms. Fisher's Exact Test was used to compare the presence of OAB symptoms between subgroups of RLS patients based on their experience of discomfort while seated or reclined and the urge to move their legs. Pearson correlation analysis examined the relationship between patient age, RLS onset age, and OAB scores. A p-value of less than 0.05 was considered statistically significant.

The study cohort comprised predominantly women (57.8%). The mean age of participants was 40.12 ± 16.47 years, and the mean age of RLS onset was 28.60 ± 17.34 years. Diabetes mellitus and hypertension were the most frequently reported underlying medical conditions. Among the 135 RLS patients, 25.9% reported urinary frequency, 45.9% experienced nocturia, 65.2% reported urgency, and 32.6% had UUI. Of the RLS patients who reported discomfort while seated or reclined (n=109), a high proportion (82.6%) also reported at least one OAB symptom. Similarly, among those with at least one OAB symptom (n=93), 78.8% reported a frequent need to move their legs. While Fisher's Exact Test showed no significant difference in the overall prevalence of OAB symptoms between groups based on discomfort or leg movement urge, a statistically significant association was found between nocturia (p=0.015) and UUI (p=0.011) with the presence of discomfort while seated or reclined. Pearson correlation analysis revealed a statistically significant positive correlation between patient age and RLS onset age (r = 0.778, p < 0.0001), as well as a significant positive correlation between RLS onset age and the OAB score (r = 0.301, p = 0.001).

The findings suggest a notable co-occurrence of urinary symptoms, indicative of potential OAB, in individuals with RLS. The significant associations observed between nocturia and UUI with discomfort during rest suggest a possible link between the sensory-motor disturbances characteristic of RLS and bladder function. The positive correlations between age and both RLS onset and OAB scores highlight the potential influence of the aging process on the development and severity of both conditions.

This study provides evidence for a significant presence of urinary issues, potentially indicative of OAB, in patients with RLS. The observed associations, particularly with nocturia and UUI, and the influence of age on symptom development underscore the need for clinicians to be aware of the potential for co-existing bladder dysfunction in individuals with RLS. Further longitudinal studies and investigations into underlying mechanisms are warranted to clarify the nature of this relationship and to inform tailored clinical management strategies that address the multi-faceted symptom burden experienced by these patients.