Table 3 Regression analysis of osteoporosis and reduced BMD in the spine and the hip (dependent variables) and disease variables (independent variables).

RR (95% CI)	Osteoporosis				Reduced BMD
	Spine L2–4		Total hip		Spine L2–4		Total hip
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 1.48)		1.31 (1.09 to 1.45)		1.07 (0.83 to 1.43)
DAS	0.89 (0.64 to 1.15)		0.89 (0.48 to 1.36)		0.89 (0.70 to 1.08)		1.10 (0.85 to 1.34)
HAQ	1.02 (0.70 to 1.36)		0.94 (0.43 to 1.54)		1.12 (0.85 to 1.39)		0.93 (0.63 to 1.27)
Total SHS	1.00 (0.98 to 1.02)		0.96 (0.91 to 1.02)		1.00 (0.98 to 1.02)		1.00 (0.98 to 1.03)

BMD, bone mineral density; DAS, Disease Activity Score, HAQ, Health Assessment Questionnaire; RR, relative risk; SHS, Sharp–van der Heijde Score.

All variables were adjusted for age, gender, menopausal status, race, smoking and alcohol status, except for themselves.

Symptom duration, RF status, DAS, HAQ and total SHS were additionally adjusted for each other.