China Glaucoma Treatment Pattern Study I-Primary Angle-Closure Glaucoma: protocol for a multicentre, retrospective, observational study.

INTRODUCTION: Primary angle-closure glaucoma (PACG) is a leading cause of irreversible blindness globally, and the number of patients with PACG rises every year. Yet, there is a lack of knowledge about the clinical characteristics, therapeutic options and profile of patients with PACG in China. Hence, we design the China Glaucoma Treatment Pattern Study Ⅰ-Primary Angle-Closure Glaucoma (Ch-GTPⅠ). The objective of this paper is to describe the design and methodology of Ch-GTP. The aim of this study is to characterise the profile and trend associated with initial PACG treatment for the last 10 years in China. METHODS: Ch-GTPⅠ is a national multicentre retrospective observational study that will randomly sample from 50 hospitals throughout China. Over 7000 patient records hospitalised for initial PACG treatment from 2011 to 2020 will be selected randomly. The data from electronic medical records will be uploaded to an encrypted online platform that will receive and collate data from all collaborating hospitals. Data abstraction and monitoring will be performed in a standardised manner by trained statisticians to ensure consistency. Systematic data cleaning will also be conducted by statisticians to ensure data integrity before final data storage. The outcomes will include four broad categories: (1) demographics, (2) clinical characteristics, (3) therapeutic strategies and procedures and (4) early outcomes at discharge. The demographic characteristics and early outcomes will be summarised using descriptive statistics. Comparative analyses of characteristics and treatment pattern changing trends for different regions and years will be used to test for significant differences (t-test or Mann-Whitney U test). ETHICS AND DISSEMINATION: The collaborating hospitals obtained local approval based on a standard ethics application from internal ethics committees or acknowledged an existent ethics approval of the leading institution with approval from internal ethics committees. Due to the retrospective nature, written informed consent from patients was waived by the ethics committee. The results will be published in academic journals and presented at national and international academic conferences. TRIAL REGISTRATION NUMBER: ChiCTR2100054643.