Design: A population-based cohort study using electronic health records of the Hospital Authority (HA) clinical management system, economic modeling, and serial cross-sectional surveys on healthcare service utilization. Setting: HA public hospitals and outpatient clinics in Hong Kong Participants: People aged ≥ 18 years with a documented diagnosis of diabetes mellitus, hypertension, cardiovascular disease, cancer, chronic respiratory disease, and chronic kidney disease; without COVID-19; attending HA services between 2010 and 2024. Main outcome measures: All-cause mortality, disease-specific outcomes, healthcare service utilization, and costs.

Methods: The annual incidence of each outcome in each year between 2010 and 2024 will be calculated. An interrupted time-series analysis to assess the changes in outcomes between pre-and-post-COVID-19 outbreak periods. Long term health economic impact of healthcare disruptions during the COVID-19 outbreak will be modeled using microsimulation. Multivariable Cox proportional hazards regression and Poisson/negative binomial regression to evaluate the effect of different modes of care on the risk of the outcomes. Implications: Findings will inform policies and practices on contingency care plans to avoid excessive morbidity and mortality and to assure the quality of care for patients with NCD as part of the territorial response to the health crisis.