Moderately decreased renal function negatively affects the health-related quality of life among the elderly Korean population: a population-based study

Background. The incidence of chronic kidney disease (CKD) is increasing in Korea, especially in the aged population. The health-related quality of life (HRQOL) of patients with chronic renal insufficiency is lower than that for the general population and a lower HRQOL is a predictor of adverse events. We report the impact of kidney function on the HRQOL and the risk factors for poor HRQOL in an elderly population living in one Korean city. Methods. This study was conducted as a part of the Korean Longitudinal Study on Health and Aging (KLoSHA) that was designed as a population-based, prospective cohort-study in a population aged > 65 years living in a satellite city of Seoul in Korea. Among 1 000 randomly selected subjects, 944 were able to complete the SF-36 questionnaires to measure HRQOL. We categorized the participants into five GFR groups: group 1: 90 mL/min/1.73 m(2) or more, group 2: 89-75 mL/min/1.73 m(2), group 3: 60-74 mL/min/1.73 m(2), group 4: 45-59 mL/min/1.73 m(2) and group 5: less than 45 mL/min/1.73 m(2). Results. Except for the general health perception and mental health scale, all the other scores of the SF-36 scales showed differences among five groups categorized according to GFR. However, the scores were significantly decreased only among participants with a GFR value of < 45 mL/min/1.73 m(2), compared to the other four GFR groups. After adjustment, the physical component summary score was the lowest in participants with GFR values < 45 mL/min/1.73 m(2). The dichotomized GFR factor with the criterion of 45 mL/min/1.73 m(2) was an independent predictor of poor physical HRQOL. Other factors, such as age, gender, duration of education, regular exercising habits, depression and a history of cardiovascular accident, were also predictors of HRQOL. A lower haemoglobin level was related to the mental component summary. Conclusion. The renal function deduced to be an important predictor of HRQOL, even in the old age group. The moderately decreased renal function of 45 mL/min/1.73 m(2) GFR was the level at which HRQOL decreased in the elderly Korean population.