title: Prevalence of and risk factors for pterygia in a rural Northern Chinese population.
abstract: OBJECTIVE
  To determine the prevalence of and associated risk factors for pterygia development in a high-latitude-dwelling Northern Chinese population.
  
  
  METHODS
  A prospective population-based survey was conducted between November 2008 and July 2009. A stratified, clustered, randomized sampling procedure was used to select 8445 subjects, aged ≥18 years, all with diagnosed, graded pterygia. Risk factors associated with the occurrence of pterygia were evaluated according to logistic regression models.
  
  
  RESULTS
  A total of 8445 residents (aged 18-94 years) from the Heilongjiang Province, China, participated in the study. Of these, 208 (2.5%) had at least one diagnosed pterygium. The prevalence of bilateral pterygia was 1.2% (95% confidence interval, CI, 1.0-1.4%). According to multivariable analysis, pterygia were significantly more likely to occur in persons aged 70-94 years than in those aged 18-39 years (odds ratio, OR, 29.0, 95% CI 13.6-61.6, p < 0.01). Pterygia were significantly associated with male sex (OR 1.9, 95% CI 1.4-2.6, p < 0.01) and outdoor work (OR 1.8, 95% CI 1.2-2.6, p < 0.01). Multivariable analysis indicated that pterygia were not associated with smoking status (OR 1.0, 95% CI 0.8-1.4) or alcohol intake (OR 1.0, 95% CI 0.7-1.4, p > 0.05).
  
  
  CONCLUSIONS
  This study details the occurrence of and risk factors for pterygia in a Chinese population residing in a rural, high-latitude, cold-climate area of Northern China. The primary risk factors for pterygia were age, male sex, and outdoor work.
authors.affiliation: Department of Ophthalmology, First Affiliated Hospital, Harbin Medical University , China and.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Li
authors.forename: Shubin
authors.initials: S
authors.lastname: Wu
authors.forename: Jieying
authors.initials: J
authors.lastname: Mai
authors.forename: Keke
authors.initials: K
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Zhen
authors.initials: Z
authors.lastname: Song
authors.forename: Di
authors.initials: D
authors.lastname: Jin
authors.forename: Haijing
authors.initials: H
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003081:Cold Climate / Q000009:adverse effects; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011625:Pterygium / Q000175:diagnosis / Q000453:epidemiology* / Q000208:ethnology; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014792:Visual Acuity; D017132:Workplace / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Cold climate; population-based; prevalence; pterygium; risk factor