Older age is associated with more MRI-detected inflammation in hand and foot joints.

OBJECTIVES: Although MRI is recommended for diagnostic use in detecting joint inflammation, its value in clinical practice has not been settled. Older symptom-free persons show more MRI-detected inflammation in their hands and feet. Within arthritis patients, a similar effect could be present (a general age effect). The association of age with MRI inflammation could also be enhanced by disease (disease-dependent age effect). Because both effects could have diagnostic consequences, we evaluated the association between age-at-onset and MRI-detected inflammation in early arthritis and RA.
METHODS: Unilateral contrast-enhanced MRI of the MCP joint, wrist and MTP joints was performed in 589 newly presenting early arthritis patients, of whom 229 had RA. Bone marrow oedema, synovitis and tenosynovitis were summed, yielding the MRI inflammation score. MRI findings were associated with age and compared with those of 193 (previously reported) symptom-free controls.
RESULTS: Early arthritis and RA-patients had, respectively, 2.6 (95% CI: 2.3, 3.0, P < 0.001) and 3.7 times (95% CI: 3.2, 4.3, P < 0.001) higher MRI inflammation scores than controls (adjusted for age). At higher age of onset, early arthritis and RA patients had higher MRI inflammation scores (1.03/year, P < 0.001). A similar effect was observed in controls (1.03/year, P < 0.001). The interaction term age*group (arthritis/RA vs controls) was non-significant (P = 0.80 and P = 0.23), suggesting that the age effect was not disease dependent. At the joint level, older RA patients had more extended MRI inflammation, but the preferential locations were similar.
CONCLUSION: Older age is associated with more MRI-detected inflammation, and the effect was similar in arthritis and controls. This age effect should be considered when interpreting hand and foot MRI for diagnostic purposes.