Exploring Disparities for Obesity in Korea Using Hierarchical Age-PeriodCohort Analysis With Cross-Classified Random Effect Models
	    		
		   		
		   			
		   		
	    	
    	 
    	10.3346/jkms.2024.39.e169
   		
        
        	
        	
        	
        		- Author:
	        		
		        		
		        		
			        		Chang Kyun CHOI
			        		
			        		
			        		
			        			1
			        			
			        		
			        		
			        		
			        		
			        		;
		        		
		        		
		        		
			        		Jung-Ho YANG
			        		
			        		;
		        		
		        		
		        		
			        		Sun-Seog KWEON
			        		
			        		;
		        		
		        		
		        		
			        		Min-Ho SHIN
			        		
			        		
		        		
		        		
		        		
		        		
		        			
			        		
			        		Author Information
			        		
		        		
		        		
			        		
			        		
			        			1. Division of Cancer Early Detection, National Cancer Control Institute, National Cancer Center, Goyang, Korea
			        		
		        		
	        		
        		 
        	
        	
        	
        		- Publication Type:Original Article
 
        	
        	
            
            
            	- From:Journal of Korean Medical Science
	            		
	            		 2024;39(20):e169-
	            	
            	
 
            
            
            	- CountryRepublic of Korea
 
            
            
            	- Language:English
 
            
            
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		        	Abstract:
			       	
			       		
				        
				        	 Background:This research article investigates the age, period, and birth cohort effects on prevalence of obesity in the Korean population, with the goal of identifying key factors to inform effective public health strategies. 
				        	
				        
				        	Methods:We analyzed data from the Korea National Health and Nutrition Examination Survey, spanning 2007–2021, including 35,736 men and 46,756 women. Using the hierarchical age-period-cohort (APC) analysis with cross-classified random effects modeling, we applied multivariable mixed logistic regression to estimate the marginal prevalence of obesity across age, period, and birth cohort, while assessing the interaction between APC and lifestyle and socioeconomic factors. 
				        	
				        
				        	Results:Our findings reveal an inverted U-shaped age effect on obesity, influenced by smoking history (P for interaction = 0.020) and physical activity (I for interaction < 0.001). The period effect was positive in 2020 and 2021, while negative in 2014 (P for period effect < 0.001). A declining trend in obesity prevalence was observed in birth cohorts from 1980s onward. Notably, disparities in obesity rates among recent birth cohorts have increased in relation to smoking history (P for interaction = 0.020), physical activity (P for interaction < 0.001), and residence (P for interaction = 0.005). Particularly, those born after 1960 were more likely to be obese if they were ex-smokers, physical inactive, or lived in rural areas. 
				        	
				        
				        	Conclusion:These findings highlight growing disparities in obesity within birth cohorts, underscoring the need for targeted health policies that promote smoking cessation and physical activity, especially in rural areas.