Obesity, metabolic abnormality, and knee osteoarthritis: A cross-sectional study in Korean women

Background. This study aimed to analyze the association between knee osteoarthritis and four body size phenotypes defined by the presence or absence of metabolic abnormality and obesity. Mehods. This was a cross-sectional study using data from 1,549 female participants of the Fifth Korean National Health and Nutrition Examination Survey. Knee osteoarthritis was defined as a Kellgren - Lawrence grade of >= 2. Metabolically abnormal state was defined as presence of more than one abnormality among five metabolic risk factors. Obesity was defined using body mass index. Participants were grouped into one of the four body size phenotypes: metabolically healthy normal weight (MHNW), metabolically abnormal but normal weight (MANW), metabolically healthy obesity (MHO), and metabolically abnormal obesity (MAO). Results. The distribution of each body size phenotype was as follows: MHNW 54.7%, MANW 30.7%, MHO 4.3%, and MAO 10.3%. Prevalence of symptomatic knee osteoarthritis was higher in MANW than in MHNW, and in MAO than in MHO. In multivariable analysis, the association between symptomatic knee osteoarthritis and the body size phenotypes was as follows (OR [95% CI]): MHNW 1.00 (reference), MANW 1.54 (1.15 -2.07), MHO 1.61 (0.83 - 3.13), and MAO 3.47 (2.35 - 5.14). Conclusions. Obesity showed closest association with knee osteoarthritis when accompanied by metabolic abnormality.