Association between Metabolically Healthy Obesity and the Risk of Incident Chronic Kidney Dysfunction

Abstract

Introduction: Chronic kidney disease (CKD), known as a global public health problem, has also become important issues threatening public health in Korea. Many epidemiological studies have investigated the association between obesity and kidney disease, supporting that obesity increases the risk of kidney disease. It has been known that most of the increased risk of CKD in obese individuals is primarily due to cardiometabolic factors associated with excess adiposity. However, not all the obese people have metabolic abnormality, and obese people with no metabolic dysfunction have been existed. They have been reported as metabolically healthy obesity (MHO) phenotype. The association between MHO and kidney dysfunction is well unknown, and it is yet to be determined whether MHO is associated with kidney dysfunction. The objective of this study is to investigate the association between MHO and the risk of incident chronic kidney dysfunction for general population of Korea.

Methods: From the Ansung and Ansan community cohort of the Korean Genome and Epidemiology Study (KoGES) data, 8,608 participants were analyzed. The main exposure of this study is MHO. This concept is a combination of metabolic phenotype and the presence or absence of obesity. The participants were divided into four groups based on the body mass index (≥28kg/㎡ as obesity) and the metabolic healthy status by using Adult Treatment Panel-Ⅲ (ATP-Ⅲ): Metabolically healthy non-obesity (MHNO), Metabolically healthy obesity (MHO), Metabolically unhealthy non-obesity (MUNO), and metabolically unhealthy obesity (MUO). The outcome of the present study is kidney dysfunction defined as eGFR <60ml/min/1.73㎡. To control the potential confounding, socio-demographic variables, behavioral factors, and biochemical factors were adjusted. Cox proportional hazard regression was used to calculate the hazard ratio (HR) with 95% confidence interval (CI) and MHNO is used as the reference. All statistical analyzes are done by using R 3.4.3.

Results: The MHO phenotype represented 4.1% (n=351) of the total analytic sample and 29.9% of the obese population. After adjusting for all covariates, the HR of MHO individuals for incident kidney dysfunction was 1.59 (95% CI, 1.24-2.04), the HR of MUNO individuals was 1.69 (95% CI, 1.51-1.89), and the HR of MUO individuals was 2.03 (95% CI, 1.73-2.38). The HRs of all groups were statistically significant higher, compared MHNO individuals, and presented a linear trend, in order of linearity: MHO, MUNO, MUO.

Conclusion: This study indicated that metabolically healthy obesity may increase the risk of incident kidney dysfunction in Korean adults. We suggest that different obese phenotype have different effect on the risk of incident kidney dysfunction and MHO is not a benign condition. Therefore, it is crucial to identify obesity-metabolic status phenotype in predicting kidney dysfunction incidence risk. Moreover, the proper prevention and treatment of chronic disease including CKD according to the obesity subtype are needed.