title: The prevalence of primary headache disorders in Nepal: a nationwide population-based study.
abstract: BACKGROUND
  Headache disorders are among the most prevalent and burdensome global public-health problems. Within countries, health policy depends upon knowledge of health within the local populations, but the South-East Asia Region (SEAR), among WHO's six world regions, is the only one for which no national headache prevalence data are available.
  
  
  METHODS
  In a cross-sectional population-based study, adults representative of the Nepali-speaking population aged 18-65 years and living in Nepal were randomly recruited using stratified multistage cluster sampling. They were visited unannounced at home by trained interviewers who used a culturally-adapted Nepali translation of the structured Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire.
  
  
  RESULTS
  There were 2,100 participants (1,239 females [59.0 %], 861 males [41.0 %]; mean age 36.4 ± 12.8 years) with 9 refusals (participation rate 99.6 %). Over half (1,100; 52.4 %) were resident above 1,000 m and almost one quarter (470; 22.4 %) lived at or above 2,000 m. The 1-year prevalence of any headache was 85.4 ± 1.5 % (gender- and age-adjusted 84.9 %), of migraine 34.7 ± 2.0 % (34.1 %), of tension-type headache (TTH) 41.1 ± 2.1 % (41.5 %), of headache on ≥15 days/month 7.7 ± 1.1 % (7.4 %) and of probable medication-overuse headache (pMOH) 2.2 ± 0.63 % (2.1 %). There was a strong association between migraine and living at altitude ≥1,000 m (AOR = 1.6 [95 % CI: 1.3-2.0]; p < 0.001). There was a less strong association between TTH and urban dwelling (AOR = 1.3 [95 % CI: 1.1-1.6]; p = 0.003), and a possibly artefactual negative association between TTH and living above 1,000 m (AOR = 0.7 [95 % CI: 0.6-0.8]; p < 0.001).
  
  
  CONCLUSIONS
  Headache disorders are very common in Nepal. Migraine is unusually so, and strongly associated with living at altitude, which in very large part accounts for the high national prevalence: the age- and gender- standardised prevalence in the low-lying Terai is 27.9 %. Headache occurring on ≥15 days/month is also common. This new evidence will inform national health policy and provide a basis for health-care needs assessment. However, research is needed to explain the association between migraine and altitude, since it may be relevant to health-care interventions.
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, St Olavs University Hospital, Trondheim, Norway.|Dhulikhel Hospital, Kathmandu University Hospital, Kavre, Dhulikhel, Nepal.
authors.forename: Kedar
authors.initials: K
authors.lastname: Manandhar
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, St Olavs University Hospital, Trondheim, Norway.|Dhulikhel Hospital, Kathmandu University Hospital, Kavre, Dhulikhel, Nepal.
authors.forename: Ajay
authors.initials: A
authors.lastname: Risal
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, St Olavs University Hospital, Trondheim, Norway.|Division of Brain Sciences, Imperial College London, London, UK.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Steiner
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, St Olavs University Hospital, Trondheim, Norway.|Pain Unit, St Olavs University Hospital, Trondheim, Norway.
authors.forename: Are
authors.initials: A
authors.lastname: Holen
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, St Olavs University Hospital, Trondheim, Norway. mattias.linde@ntnu.no.|Norwegian Advisory Unit on Headaches, St Olavs University Hospital, Trondheim, Norway. mattias.linde@ntnu.no.
authors.forename: Mattias
authors.initials: M
authors.lastname: Linde
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D051270:Headache Disorders, Primary / Q000453:epidemiology*; D051271:Headache Disorders, Secondary / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology; D009390:Nepal / Q000453:epidemiology; D015995:Prevalence; D018781:Tension-Type Headache / Q000453:epidemiology; D055815:Young Adult
keywords: Medication-overuse headache; Migraine; Nepal; Public health, population-based study, prevalence; South-East Asia Region, Global campaign against headache; Tension-type headache