Decomposition of socioeconomic inequalities in glaucoma knowledge in Taiwan

Glaucoma knowledge is strongly associated with medication adherence and preventive behavior. Studies have frequently reported socioeconomic inequalities in glaucoma knowledge. This study aimed to decompose such inequalities. Decomposition analysis enables the design of policies directly targeting the underlying causes of inequality.

We performed a cross-sectional survey from January 1, 2019 to June 30, 2019, at the departments of ophthalmology of 2 medical centers belonging to a hospital chain in northern Taiwan. Socioeconomic inequalities in glaucoma knowledge were ranked based on 3 aspects of socioeconomic status (SES): (1) education, (2) income, and (3) self-perceived financial status. The concentration index was calculated and decomposed using decomposition analysis. Elasticity and marginal effects were estimated for each decomposed factor.

In total, 1,203 patients completed the survey. Both measures of glaucoma knowledge and overall glaucoma knowledge score significantly contributed to the progressivity of knowledge inequalities (pro-high-SES inequalities). The concentration index for overall knowledge score with respect to education was 0.166 (p<0.001). Both objective and subjective measures of SES were associated with pro-high-SES inequalities. Our decomposition analysis revealed that demographic factors and attitudinal factors such as the level of concern regarding developing glaucoma contributed significantly to SES-based inequalities in glaucoma knowledge.

Our decomposition analysis provided empirical evidence regarding the underlying causes of SES-based inequalities in glaucoma knowledge. Efforts to improve glaucoma knowledge should consider specific factors that drive SES-based inequalities, such as age, sex, and concern about vision health, to ultimately achieve low SES-based inequalities.