Demographic characteristics of the participants.

Geriatric syndrome (GS) is the prevalence of a group of phenotypes in older people. Functional decline, cognitive impairment, and frailty are common phenotypes that burden individuals, families, and the healthcare system. Policies targeting GS require information on socioeconomic background of older people, which is scarce in Thailand. We investigated socioeconomic inequality associated with GS using the concentration index and further explained the contributions of socioeconomic status and sociodemographic variables to inequality. Nationally representative data of 7,365 individuals aged 60 years and above from the 5th National Health Examination Survey of 2013 were analyzed. The survey used a physical examination, blood test, and questionnaire interviews to elicit personal information, health status, and household assets. The wealth index was used as the main indicator of socioeconomic status, and participants with missing wealth index data were excluded. Three GS phenotypes—frailty, functional impairment (FI) and neurocognitive dysfunction (NCD)—were included. An indirectly standardized concentration index (Cis) and a 95% confidence interval were used to represent the horizontal equity of the three phenotypes. Contributions to the concentration index (CC)—contribution to a more or less equitable GS distribution—were decomposed and shown in terms of percentage and direction. All GS phenotypes were found to be concentrated in the elderly poor (Cis of FI, frailty, and NCD = -0.068, -0.092, and -0.182, respectively). Work status contributes to a more equitable GS distribution in all the phenotypes (� in FI, frailty, and NCD = -1.7%, -5.1%, and -2.0%, respectively), whereas types of insurance schemes made bidirectional contributions to the equity of GS. Policies should be adopted to help prevent GS among poor individuals, provide them with an equal opportunity of access to health schemes and ensure opportunities for older Thai individuals to work.