Table 3.

Generalized estimating equations (conducted on non‐imputed data) of the association between ACPA IgG levels at inclusion and baseline and longitudinal change in absolute BMD and Z scores^*

	Absolute BMD, g/cm2	Z score
Lumbar spine
Baseline	−0.002 (−0.017, 0.126)	0.001 (−0.129, 0.132)
Yearly change	0.001 (−0.001, 0.002)	0.004 (−0.009, 0.017)
Left hip (total hip)
Baseline	0.007 (−0.006, 0.019)	0.074 (−0.016, 0.165)
Yearly change	0.0003 (−0.002, 0.002)	−0.004 (−0.012, 0.004)

^*Values are the β (95% confidence interval [95% CI]) for the association between anti–citrullinated protein antibody (ACPA) IgG levels at inclusion and absolute bone mineral density (BMD) and Z scores at baseline, and yearly change in absolute BMD and Z scores per 10‐fold (or log₁₀) difference in ACPA IgG levels. Analyses were performed in 268 Dutch patients with rheumatoid arthritis who were positive for anti–citrullinated protein antibodies (ACPAs). Log₁₀ transformation on ACPA IgG levels was applied in order to achieve normal distribution of levels. Models were adjusted for the following baseline variables: age, sex, body mass index, symptom duration, and smoking status. Models were also adjusted for the following longitudinal time‐varying measurements: Disease Activity Score, prednisone intake, Health Assessment Questionnaire score, C‐reactive protein levels, and serum 25‐hydroxyvitamin D levels.