A follow-up study on restless legs syndrome in chronic obstructive pulmonary disease population

Restless legs syndrome (RLS) is prevalent in patients with chronic obstructive pulmonary disease (COPD). No large population-based cohort study has assessed the relationship. We evaluated the incidence of RLS among COPD patients by sociodemographic status (SES) and comorbidity using insurance claims data of Taiwan.

From the database, we established a cohort consisting of 77,831 individuals aged ≥ 20 years newly diagnosed with COPD from 2000 to 2013. We also identified same number of individuals without COPD as the comparison cohort, frequency matched by sex, age and index year. Both cohorts were followed up to the end of 2013 to estimate the incidence and hazard ratio (HR) of developing RLS.

The incidence of RLS was 2.2-fold higher in COPD patients than in those free of COPD (6.67 and 3.08 per 10,000 person-years), with an adjusted HR (aHR) 1.68 (95% CI 1.41-2.01) after controlling for covariates. The incidence rates in both cohorts increased with age and higher in low socioeconomic group. The risk of RLS increased further among COPD patients with additional comorbidities. Compared to those without COPD and comorbidity, the aHR was 7.93 (95% CI 1.11-57.8) for those with iron deficiency, 3.95 (96% CI 1.92-8.13) with Parkinson's disease, 2.85 (95% CI 1.05-7.72) with polyneuropathy, or 1.81 (95% CI 1.14-2.87) with diabetes.

Patients with COPD are at an increased risk of developing RLS regardless of gender, age and occupation. The COPD patients with comorbidities should be particularly cautious about the RLS risk.