Impaired arterial function associated with thinning of cortical bone in rheumatoid arthritis

To evaluate the association between peripheral arterial function and cortical bone thickness in rheumatoid arthritis (RA).

In a cross-sectional study, we measured the combined cortical thickness (CCT) of the second metacarpal bone from hand radiographs, and the ankle-to-arm systolic blood pressure ratio, also known as ankle-brachial index (ABI), in RA patients. We evaluated the association between the 2 using multinomial logistic regression.

We obtained CCT and ABI measurements in 588 RA patients. The mean +/- SD CCT was 3.62 +/- 1.16 mm. The proportion of patients with > or =1 ABI value < or =0.9, indicating obstructed lower limb arteries, increased from 18 (9.2%) of 191 patients in the highest CCT tertile to 25 (12.5%) of 200 in the middle CCT tertile to 38 (19.2%) of 198 in the lowest CCT tertile (P for trend 0.005). We noted a similar pattern for ABI values >1.3, indicative of arterial incompressibility (frequencies in high, middle, and low CCT tertiles were 4.7%, 9.5%, and 19.9%, respectively; P for trend < or =0.001). These trends remained significant after multivariable adjustment for potential confounders. After adjustment for the manifestations of RA and cumulative glucocorticoid dose, the association between CCT and arterial obstruction remained significant, but that with arterial incompressibility weakened considerably.

There is an association between metacarpal cortical bone thinning and obstruction or incompressibility of the peripheral arteries in RA. The association with incompressibility may be mediated by systemic inflammation and/or glucocorticoids, but that with obstruction is independent of a wide array of potential confounders. Clinicians should be alert to the possibility of impaired arterial function RA patients with thinned metacarpal cortical bone.