Table 4 Multivariate regression analysis of osteoporosis and reduced BMD in the spine and the hip (dependent variables) and demographic and disease variables (independent variables)

RR (95% CI)	Osteoporosis		Reduced BMD
RR (95% CI)	Spine L2–4	Total hip	Spine L2–4	Total hip
Male gender	2.54 (0.88 to 6.16)	2.05 (0.73 to 4.56)	1.80 (1.23 to 2.41)	1.43 (0.74 to 2.47)
Postmenopausal status	1.93 (1.17 to 3.07)	1.60 (0.78 to 3.85)	2.05 (0.99 to 4.55)	1.45 (0.66 to 3.15)
BMI, kg/m²	0.90 (0.84 to 0.96)	0.74 (0.58 to 0.90)	0.99 (0.94 to 1.04)	0.92 (0.87 to 0.97)
Familial osteoporosis	1.54 (0.93 to 2.02)	1.15 (0.44 to 3.20)	2.16 (1.23 to 3.39)	2.47 (1.30 to 4.00)
Symptom duration, weeks	1.001 (0.99 to 1.00)	1.004 (1.00 to 1.01)	1.001 (0.99 to 1.00)	1.002 (1.00 to 1.00)
Positive RF	1.17 (0.87 to 1.38)	1.24 (0.64 to 2.48)	1.31 (1.09 to 1.45)	1.07 (0.83 to 1.43)

BMD, bone mineral density; BMI, body mass index; RF, rheumatoid factor; RR, relative risk.
All variables were adjusted for age, gender, menopausal status, race, smoking and alcohol status, except for themselves.
Symptom duration, rheumatoid factor status, Disease Activity Score, Health Assessment Questionnaire and total Sharp–van der Heijde score were additionally adjusted for each other.