Prevalence and risk factors for pterygium: a cross-sectional study in Han and Manchu ethnic populations in Hebei, China

Aims To investigate the prevalence, ethnic differences and associated risk factors for pterygium in Han and Manchu populations aged 40–79 years in Hebei province, China. Design Cross-sectional study, as a part of the China National Health Survey. Setting Hebei province, China. Participants A multistage cluster sampling method with urbanisation level-based stratification was used to select participants for this study. A total of 4591 individuals over 40 years were recruited for this study. Inclusive criteria: (1) residents who had been living in Hebei for more than 1？year; (2) Han individuals with both parents being Han, or Manchu individuals with both parents being Manchu; (3) underwent ophthalmic examinations and (4) information in the questionnaire was complete. Main outcome measures Multiple logistic regression analysis was used to evaluate the association between pterygium prevalence and factors of interest. Results A total of 3790 individuals (2351 Hans and 1439 Manchus) met the study criteria, of which 248 were diagnosed with pterygium (6.5%). There was no significant difference between the prevalence rates in Hans (6.2%) and Manchus (7.2%) (p=0.232). Multivariate analysis revealed that the risk factors for grade 2 or higher pterygium were increasing age (p<0.001) and rural residence (OR 1.83; 95% CI 1.11 to 3.02; p=0.018), while the protective factors include gender (female) (OR 0.58; 95%？CI 0.37 to 0.88; p=0.011), cigarette smoking (OR 0.53; 95%？CI 0.34 to 0.83; p=0.005) and myopia (OR 0.50; 95%？CI 0.33 to 0.77; p=0.002). Premature menopause (OR 2.66; 95%？CI 1.05 to 6.72; p=0.038) increased the risk of grade 2 or higher pterygium in females, while higher high-density lipoprotein (HDL) (OR 1.94; 95%？CI 1.08 to 3.47; p=0.027) was a risk factor of grade 2 or higher pterygium in males. Conclusion The overall prevalence of pterygium in Han and Manchu population in Hebei, China was approximately 6.1%. There were no differences in the prevalence of pterygium between Hans and Manchus, and the race was not a risk factor. This is the first study to report on the positive association between premature menopause and pterygium in females and between higher HDL levels and pterygium in males