Chinese observational prospective study of ageing population with chronic kidney disease (C-OPTION): a study protocol.

INTRODUCTION: The proportion of elderly people is steadily rising worldwide, especially in low-income and middle-income countries, including China. Chronic kidney disease (CKD) is a common disorder in older people. However, little is known about the epidemiology of CKD and its consequences among the elderly. Improvements on clinical guidelines and healthcare policies for this population are required. This study aims to examine the risk factors for progression of CKD among the elderly and develop models to identify subgroups who are at high risk.

METHODS AND ANALYSIS: This is a prospective, multicentre, cohort study. The study population comprises ~3000 patients with predialysis CKD, aged ≥65 years, recruited between March 2016 and December 2017. After the baseline assessments, these patients will be followed for 5 years or until the occurrence of primary outcomes. Assessments that include anthropomorphic measures, laboratory tests, questionnaires, and blood and urine specimen collection will be performed at baseline and at follow-ups. Data on demographic information, cognitive function, depression, risk of malnutrition, physical activity and quality of life will be collected. The primary outcomes are incidence of end-stage renal disease, loss of renal function (≥40% decline in glomerular filtration rate from baseline), and death. The secondary outcomes are acute coronary syndrome, hospitalisation for heart failure or unstable angina, cerebrovascular events, and peripheral arterial disease.

ETHICS AND DISSEMINATION: This study protocol has been approved by the ethics committees of the Chinese People's Liberation Army General Hospital and the participating centres. All the participants gave written informed consent before data collection. The findings of the study will be published in peer-reviewed journals and will be presented at national or international conferences.

TRIAL REGISTRATION NUMBER: NCT03246204; Pre-results.