Table 3.

Associations between obesity and the risk of development of rheumatoid arthritis in the subset with available waist circumference measurement

	All	Men	Women	Development of seropositive RA	Development of seronegative RA
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
BMI (OR per 5 kg/m2)	1.31 (1.05, 1.64)	1.91 (1.15, 3.19)	1.19 (0.92, 1.53)	1.28 (0.99, 1.65)	1.52 (0.88, 2.64)
Waist circumference (OR per cm)	1.02 (1.01, 1.04)	1.05 (1.01, 1.09)	1.01 (0.99, 1.04)	1.02 (1.00, 1.04)	1.02 (0.98, 1.07)
Abdominal obesity	1.40 (0.92, 2.14)	3.57 (1.50, 8.51)	1.04 (0.63, 1.71)	1.36 (0.85, 2.17)	1.21 (0.41, 3.62)
No abdominal obesity	Reference	Reference	Reference	Reference	Reference
Obesity	2.95 (1.20, 3.51)	3.56 (1.27, 9.96)	1.68 (0.88, 3.23)	1.98 (1.07, 3.67)	2.18 (0.62, 7.67)
Overweight	0.84 (0.52, 1.36)	1.12 (0.41, 3.04)	0.77 (0.44, 1.35)	1.02 (0.60, 1.74)	0.31 (0.09, 1.07)
Normal or underweight	Reference	Reference	Reference	Reference	Reference
Obesity	2.12 (1.35, 3.63)	3.37 (1.37, 8.31)	1.88 (1.02, 3.46)	1.96 (1.12, 3.45)	3.66 (1.15, 11.7)
No obesity	Reference	Reference	Reference	Reference	Reference

Associations between abdominal obesity (measured by waist circumference) or being overweight and/or obese (as assessed by body mass index (BMI)) and the risk of onset of rheumatoid arthritis (RA) in all individuals, men and women separately, or divided based on whether the patients (cases) later developed seropositive or seronegative RA. In the subset the individuals with available measurements of waist circumference (from the MONICA cohort and from the VIP cohort from 2004 and onwards) were included. Results from conditional logistic regression analyses are presented adjusted for education and smoking, in case–control sets matched for age, sex, cohort, and year of health examination. Abdominal obesity was defined as a waist circumference ≥102 cm (men) or ≥88 cm (women). Obesity was defined as BMI ≥30 kg/m², and overweight as BMI >25 and <30 kg/m². OR odds ratio