Characteristics and risk factors of rheumatoid arthritis in the United States: an NHANES analysis.

Background: We examined the United States National Health and Nutrition Examination Survey (NHANES) database to determine factors associated with rheumatoid arthritis (RA) in adults 20 to 55 years of age.

Methods: NHANES data collected between 2007 and 2014, excluding the 2011-2012 period, were used. Subjects were divided into those with and without RA. Demographic, clinical, and lifestyle factors were compared between the groups.

Results: After applying inclusion/exclusion criteria, 8,789 persons were included in the study (8,483 without RA, 306 with RA). Multivariable analysis indicated that advanced age (odds ratio [OR] = 1.09, 95% CI [1.07-1.11], P  < 0.001), regular smoking (OR = 2.19, 95% CI [1.49-3.21], P  < 0.001), diabetes (OR = 2.00, 95% CI [1.35-2.95], P  = 0.001), obesity (reference, normal or underweight; OR = 3.31, 95% CI [2.05-5.36], P  < 0.001), and osteoporosis (OR = 3.68, 95% CI [1.64-8.22], P  = 0.002) were positively associated with RA. Covered by health insurance (OR = 1.81, 95% CI [1.12-2.93], P  = 0.016) and living in poverty (OR = 2.96, 95% CI [1.88-4.65], P  < 0.001) were also associated with having RA. Mexican American, Hispanic white or other Hispanic ethnicity (reference, non-Hispanic white; OR = 0.54, 95% CI [0.31-0.96], P  = 0.036), appropriate sleep duration (about 6-11 h, OR = 0.46, 95% CI [0.32-0.65], P  < 0.001), and insufficient vitamin A intake (reference, recommended; OR = 0.70, 95% CI [0.50-0.98], P  = 0.036) were negatively associated with RA.

Discussion: Some factors associated with RA are potentially modifiable.