Prevalence and risk factors for pterygium in six rural regions of Yunnan Province

Abstract

Objective: To investigate the prevalence and risk factors of pterygium in the rural population aged 40 years and above of 12 ethnic groups in 6 regions of Yunnan Province. Methods: This was a cross-sectional study. According to the method of multistage stratified sampling, samples of the rural population aged 40 years and above were collected from 12 ethnic groups (Han, Yi, Tibetan, Lisu, Bai, Naxi, Zhuang, Miao, Dai, Jingpo, Hani, and Lahu) in six areas (Diqing, Lijiang, Wenshan, Dehong, and Pu'er) of Yunnan Province from March 2019 to November 2019. Anterior segment examination was carried out in the target population with a hand-held slit-lamp, according to which pterygium was diagnosed, while the posterior segment of the eye was assessed by direct ophthalmoscopy. A field questionnaire survey was also conducted. A two-level model was used to study the effects of the location, nationality, sex, age, occupation, outdoor activities, smoking, and alcohol consumption on the prevalence of pterygium, with the ethnic group as the high level and the individual as the low level. Results: Among 9 617 subjects, the total prevalence rate of pterygium was 22.6%, which was adjusted to 19.6% according to the age and gender data of the Statistics Bureau of Yunnan Province. There was significant difference in prevalence of pterygium among six regions after adjusting for age and sex (χ2=146.50, P<0.001). The prevalence of pterygium was the highest in Wenshan (29.4%), followed by Chuxiong (24.4%), Diqing (17.5%), Pu'er (17.5%), Dehong (15.8%), and Lijiang (15.7%) (χ2=146.50, P<0.001). The results of the single factor analysis showed that there was statistically significant difference among different groups of age, gender, nationality, location, history of smoking, drinking, eating habits, sleeping time, continuous use of eye drops, temperature, humidity, altitude, longitude, latitude, and ultraviolet ray (P<0.05). However, the results of the multivariate analysis showed that the main risk factors of pterygium were female(OR=1.357,95%CI:1.173~1.568), advanced age(OR=1.540,95%CI:1.301~1.823), location(OR=1.713,95%CI:1.000~2.667), continuous use of eye drops(OR=1.177,95%CI:1.034~1.340), and more than 40 years of alcohol drinking(OR=1.525, 95%CI: 1.108~2.099), and the protective factor was more than 40 years of smoking(OR=0.723,95%CI:0.544~0.960). Conclusions: The prevalence of pterygium varies greatly among different regions in Yunnan Province. The main factors affecting the prevalence are sex, age, region, smoking history, and drinking history.