Prevalence of and risk factors for pterygia in a rural Northern Chinese population.

Purpose: To determine the prevalence of and associated risk factors for pterygia development in a highlatitude-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.