Restless legs syndrome in patients with chronic obstructive pulmonary disease.

OBJECTIVE To evaluate the prevalence of restless legs syndrome (RLS) in patients with chronic obstructive pulmonary disease (COPD) and the relationship between RLS and clinical/laboratory findings of COPD. METHODS One hundred and thirty-four COPD patients without secondary causes of RLS were included. Thirty-nine (29.1%) patients were diagnosed with RLS and classified as Group 1. The control group consisted of 65 age-matched COPD patients without RLS. Group 1 was divided into subgroups according to the Johns Hopkins Severity (JHS) scale. Patients with a score of 0, 1, or 2 were classified as JHS 0-2 and those with a score of 3 as JHS 3. Group 1 and the control group and subgroups were compared for clinical and laboratory characteristics. RESULTS We found that the duration of COPD was longer and that airway obstruction, hypercapnia, and hypoxia were more evident in patients with RLS than those without. Similar differences were also detected between JHS subgroups 3 (more severe) and 0-2. Polyneuropathy frequency was significantly higher in Group 1 compared to controls. However, Group 1 subgroups showed a similar frequency of polyneuropathy. In a multivariate analysis, hypercapnia made a significant independent contribution to both JHS 0-2 and JHS 3 patients when RLS severity was set as the dependent variable. Polyneuropathy and the duration of COPD were significant independent variables for patients in the JHS 3 subgroup. Polyneuropathy was the strongest predictor for the JHS 3 patients. CONCLUSIONS We conclude that RLS is frequent in COPD, particularly in patients with severe hypoxemia/hypercapnia and in late stages of the disease.