Rural and Urban Disparities in Frailty and Aging‐Related Health Conditions in Korea

To the Editor: Disparities in health status between urban and rural dwellers have been demonstrated in several populations.1-4 Whether rural dwellers have a greater burden of frailty and aging-related health conditions than urban dwellers is not known. Understanding such differences may help to customize medical and public health interventions for aging populations. To this end, the prevalence of frailty and aging-related conditions in two population-based cohorts of rural and urban dwellers in Korea was determined: the Aging Study of PyeongChang Rural Area (ASPRA) and the Korean Longitudinal Study on Health and Aging (KLoSHA). The ASPRA cohort, established in 2014, is a population-based cohort study of 382 rural dwellers aged 65 and older residing in two towns in PyeongChang County (total population size: 43,660; 22.0% aged ≥65), which is located 180 km east of Seoul. This cohort includes 95% of the eligible people in the study area, and its sociodemographic characteristics are similar to those of a national sample of the rural population, except that it had higher proportions of individuals who were working in agriculture (53.4% vs 25.1%) and who had no formal education (44.8% vs 22.6%). In 2005, the KLoSHA enrolled 693 urban dwellers aged 65 and older living in Seongnam City, one of the largest satellite cities of Seoul (total population: 931,019; 6.6% aged ≥65).5-7 Data of 484 individuals randomly sampled from the census were analyzed. In both studies, participants underwent a comprehensive evaluation by geriatricians, including the Cardiovascular Health Study (CHS) frailty criteria,8 multimorbidity, activity of daily living (ADL) and instrumental activity of daily living (IADL) disability, Mini-Mental State Examination, Center for Epidemiologic Studies Depression Scale, Mini-Nutritional Assessment Short Form, and incontinence. The prevalence of frailty and of each condition of rural and urban dwellers was compared after adjusting for age and sex using linear regression for continuous variables and logistic regression for dichotomous variables. To determine a single screening test for frailty, the discrimination ability of each frailty component in identifying frailty was evaluated using C statistics. Rural dwellers from the ASPRA cohort were older (74.4 vs 70.9) than urban dwellers from the KLoSHA cohort and more likely to be female (56.3% vs 52.5%) and have less education (5.1 vs 7.9 years) (Table 1). Rural dwellers had higher prevalence of frailty than urban dwellers (17.4% vs 10.3%), mainly because of a higher prevalence of exhaustion (33.2% vs 23.8%) and weakness (50.9% vs 15.8%), although they were less likely to have a slow walking speed (8.4% vs 26.9%). The frailty components with the highest discriminative ability were low activity (C statistic 0.90) in rural dwellers and weight loss (C statistic 0.88) in urban dwellers. Rural dwellers had a higher prevalence of multimorbidity (31.9% vs 21.3%), ADL disability (14.9% vs 5.4%), and IADL disability (38.5% vs 18.2%). Cognitive dysfunction, depression, risk of malnutrition, and incontinence did not differ between the two populations. Older Koreans living in rural communities have a disproportionately greater burden of frailty and aging-related health conditions than those in urban communities. Better health status of urban dwellers has been previously reported,1-4 but health status was self-reported and did not include aging-related conditions. Frailty was assessed using the validated CHS criteria,8 and remarkable differences in frailty components were found between rural and urban dwellers. Although mobility impairment is generally considered the single best marker of frailty,9 low activity outperformed other components in identifying frailty in rural dwellers, and weight loss outperformed other components in urban dwellers. These results suggest that the characteristics of the population should influence the choice of a screening test for frailty. A small fraction of rural dwellers had slow walking speed, and almost half had weakness. Multimorbidity and disability were more common in rural dwellers. These findings call for medical and public health interventions targeting different components of frailty for rural dwellers. Limited access to health care and resources in rural areas are barriers to eliminating disparities in age-related health conditions between urban and rural populations. The current study highlights that the choice of frailty screening tests and interventions need to be customized to the characteristics of rural and urban populations. We thank our study participants and their families in Haanmi-Li and Gaesu-Li, PyeongChang County, Gangwon Province, South Korea. We are also grateful to the public health professionals at the Community Health Posts and County Hospital who provided administrative support. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Dr. Dae Hyun Kim provides paid consultative services on geriatrics care to the Alosa Foundation, a nonprofit educational organization that has no relationship to any drug or device manufacturers.