Prevalence and Overlap of Cardiovascular, Kidney, and Metabolic Diseases in Korea: A Population-based Study

This study tests the prevalence and characteristics of overlapping obesity, type 2 diabetes (T2D), cardiovascular disease (CVD), chronic kidney disease (CKD), and metabolic dysfunction-associated steatotic liver disease \[MASLD/Metabolic Dysfunction-Associated Steatohepatitis (MASH)\], osteoarthritis, hypertension, and dyslipidemia. The purpose of the study is to measure how common cardiovascular, kidney, and metabolic diseases are in the Korean adult population and how often they occur together (overlap) over time (2013-2023). Participants will not receive any study medicine as this is an observational analysis of existing survey data. The study does not involve a new investigational drug; it analyses health and outcome data collected in routine practice and national surveys.

Inclusion Criteria: * For an eligible participant, all inclusion criteria must be answered "yes". Primary Analysis: 1. Enrolled in the Korean National Health Insurance Service (NHIS) with valid insurance eligibility during the assessment year. 2. Adults aged 19 years or older at the index date (January 1 of each assessment year, annually from 2013 to 2023). Secondary Analysis (Subgroup Cohorts): 1. Enrolled in the Korean National Health Insurance Service (NHIS) with valid insurance eligibility during the cohort entry year. 2. Adults aged 19 years or older at the cohort entry date (i.e., the index date defined per the relevant subgroup cohort in) (per the SAP). 3. Meets the operational definition of the index disease or state for one of the four pre-specified subgroup cohorts (MASLD, HF, CKM stage, or High obesity) (per the SAP). Exclusion Criteria: * For an eligible participant, all exclusion criteria must be answered "no". Primary Analysis: 1. Individuals with missing age or sex information in the NHIS database. 2. Individuals with less than 1 year of continuous enrollment prior to the index date (to ensure adequate lookback period for disease identification). Secondary Analysis (Subgroup Cohorts) 1. Individuals with missing age or sex information in the NHIS database. 2. Individuals with less than 1 year of continuous NHIS enrollment prior to the cohort entry date (to ensure adequate washout for incident-case ascertainment). 3. Individuals with prior record of respective disease within the 1-year lookback window