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.