title: Is restless legs syndrome associated with chronic mountain sickness?
abstract: BACKGROUND
  Restless legs syndrome (RLS) and chronic mountain sickness (CMS) share physiological traits. Our objective was to explore a possible association between RLS and CMS.
  
  
  METHODS
  We carried a cross-sectional study with male subjects living between 4100 and 4300 m above sea level. Participants underwent a clinical interview, physical examination, electrocardiographic (EKG) recording, and spirometry. We classified subjects into CMS, Limbo, and healthy high-altitude dwellers (hHAD), according to their Quinghai score and hematocrit levels. We applied the "Paradigm of questions for epidemiological studies of RLS," The International Restless Leg Syndrome Study Group Scale, and the Pittsburgh Sleep Quality Index. Logistic regression analysis was used to determine the association between variables.
  
  
  RESULTS
  Seventy-eight male subjects were included. Forty subjects were hHAD, 23 were CMS patients, and 15 participants were considered as Limbo. CMS and Limbo subjects had a higher frequency of RLS (p <0.05). Limbo subjects had the highest severity score for RLS. There were no differences in age, body mass index (BMI), or tobacco use between RLS patients and non-sufferers. In the multivariate analysis, CMS was not associated with RLS diagnosis. Oxygen saturation (p = 0.019), poor sleep quality (p <0.01), and Quinghai score of ≥6 (p = 0.026) were independently associated with RLS diagnosis.
  
  
  CONCLUSIONS
  Our results did not show a direct association between RLS and CMS; however, RLS was associated with reduced oxygen saturation. Hence, RLS could represent an early clinical manifestation of hypoxia, or, in CMS natural history, an early sign of maladaptation to high altitude.
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru; Faculty of Medicine, Universidad Peruana Cayetano Heredia, Avenida Honorio Delgado 430, Lima 31, Peru. Electronic address: dvizcarra@yahoo.com.
authors.forename: Darwin
authors.initials: D
authors.lastname: Vizcarra-Escobar
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mendiola-Yamasato
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru.
authors.forename: Jorge
authors.initials: J
authors.lastname: Risco-Rocca
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Mariños-Velarde
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru.
authors.forename: Alan
authors.initials: A
authors.lastname: Juárez-Belaunde
authors.affiliation: Hypnos, Instituto del Sueño, Clinica San Felipe, Avenida Gregorio Escobedo 650, Lima 11, Peru.
authors.forename: Victor
authors.initials: V
authors.lastname: Anculle-Arauco
authors.affiliation: Laboratory of Human Adaptation, Laboratories for Research and Development (LID), Center of Research for Integral and Sustainable Development (CIDIS), Faculty of Sciences and Philosophy, Universidad Peruana Cayetano Heredia, Avenida Honorio Delgado 430, Lima 31, Peru.
authors.forename: María
authors.initials: M
authors.lastname: Rivera-Chira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000532:Altitude Sickness / Q000097:blood / Q000150:complications* / Q000453:epidemiology; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D006400:Hematocrit; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010568:Peru / Q000453:epidemiology; D012148:Restless Legs Syndrome / Q000097:blood / Q000209:etiology*; D012720:Severity of Illness Index; D013147:Spirometry; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Chronic mountain sickness; Hypoxia; Peru; Restless legs syndrome