Adult invasive pneumococcal disease in the Republic of Korea: Risk medical conditions and mortality stratified by age group

•National immunization of the elderly with the 23-valent polysaccharide vaccine (PPSV23) was implemented in Korea in 2013.•Overall in-hospital mortality was 34.2% for adult invasive pneumococcal disease (IPD) and 51.0% for patients ≥75 years of age.•Mortality risks were older age, higher bacteremia score, and immunocompromised status.•An effective vaccination strategy for those at higher risk of IPD is needed. This study aimed to characterize the risk factors for mortality in adult patients with invasive pneumococcal disease (IPD) stratified by age groups, after implementation of the national immunization program of 23-valent polysaccharide vaccine (PPSV23) for those aged ≥65 years in the Republic of Korea (ROK). Clinical data and pneumococcal isolates from adult patients with IPD (≥18 years of age) were collected prospectively from 20 hospitals through the nationwide surveillance program from March 2013 to October 2015. A total of 319 patients with IPD were enrolled. Median age was 69 years. Overall in-hospital mortality was 34.2%: 17.1% in those aged 18–49 years, 23.7% in those aged 50–64 years, 33.0% in those aged 65–74 years, and 51.0% in those aged ≥75 years (p