Epidemiologic study of pterygium in Taiwan

To investigate the incidence, prevalence, and factors related to pterygium in Taiwan.

An ecological study METHODS: We analyzed a random sample of 1 million individuals in Taiwan drawn from the National Health Insurance Database (NHIRD), established in 2005, for the period 2000 to 2011. Patients with pterygium were identified using ICD-9-CM diagnostic codes. The prevalence and annual age- and gender-adjusted incidence of pterygium were calculated for each county in Taiwan. The risk factors including ultraviolet (UV) exposure, outdoor occupation, educational level, and average socioeconomic status of each county of each index year were identified. Univariate and backward elimination multivariate selection by the mixed-effects model were performed to identify significant risk factors related to the incidence of pterygium in Taiwan.

A total of 22,063 individuals with pterygium (10,125 men and 11,938 women) were identified in this study. The prevalence of pterygium was 2.14% in the overall population and 3.48% in the population aged 40 years or older. The occurrence of pterygium was greater in women. In addition, this study demonstrated that UV exposure and low educational level are correlated with the age- and gender-adjusted incidence of pterygium.

Our study is the first to use the NHIRD to determine the prevalence (2.14%) and annual age- and gender-adjusted incidence of pterygium among the general population of Taiwan. The relationship of pterygium with UV exposure and educational level suggests a complex and multifactorial etiology for this disease.