Table 2.
Association of BMI with MRI-detected inflammation in patients with RA, early arthritis patients with other arthritides, and asymptomatic volunteers
| Rheumatoid arthritis (n = 195) | Other arthritides (n = 159) | Asymptomatic volunteers (n = 193) | ||||
|---|---|---|---|---|---|---|
| β (95 % CI) | p value | β (95 % CI) | p value | β (95 % CI) | p value | |
| Univariable | ||||||
| BMI | 0.97 (0.94–1.00) | 0.024 | 1.082 (1.041–1.13) | <0.001 | 1.029 (1.001–1.057) | 0.040 |
| Multivariable | ||||||
| Model 1 | ||||||
| BMI | 0.96 (0.94–0.99) | 0.005 | 1.036 (1.00–1.075) | 0.054 | 1.022 (1.001–1.044) | 0.040 |
| Age | 1.025 (1.017–1.033) | < 0.001 | 1.033 (1.024–1.041) | < 0.001 | 1.031 (1.025–1.036) | < 0.001 |
| Gender | 1.13 (0.89–1.44) | 0.30 | 0.88 (0.67–1.15) | 0.34 | 1.010 (0.84–1.21) | 0.92 |
| Model 2 | ||||||
| BMI | 0.96 (0.94–0.99) | 0.003 | 1.039 (1.001–1.078) | 0.043 | NA | |
| Age | 1.022 (1.014–1.030) | < 0.001 | 1.030 (1.021–1.039) | < 0.001 | NA | |
| Gender | 1.12 (0.89–1.41) | 0.35 | 0.93 (0.71–1.23) | 0.62 | NA | |
| CRP | 1.007 (1.003–1.012) | 0.001 | 1.002 (0.998–1.006) | 0.29 | NA | |
| ACPA positivity | 0.96 (0.77–1.20) | 0.72 | 1.55 (0.75–3.20) | 0.24 | NA | |
Total inflammation scores were log-transformed for regressions. Regression coefficients presented are back-transformed (10β and 1095 % CI). Therefore, the effect size (β) can be interpreted as the fold increase in MRI-detected inflammation per point increase in BMI. Thus, an effect size of < 1 means a decrease in MRI-detected inflammation per unit increase in BMI and an effect size of > 1 means an increase in MRI-detected inflammation per unit increase in BMI. The raw beta coefficients are presented in Additional file 3
BMI body mass index, MRI magnetic resonance imaging, RA rheumatoid arthritis, NA not assessed, CRP C-reactive protein, ACPA anti-citrullinated protein antibody