KCPS-II is a large blood-based cohort study with long-term follow-up via linkage of routine, nationwide medical examinations and records for mortality and hospitalization. Participants visiting 18 health promotion centres across South Korea for regular health check ups, health issues, referrals, mandatory work examinations or other reasons were recruited to join the study. At baseline, the cohort was comprised over 156,000 participants aged between 20 and 84 years.