Methotrexate, Blood Pressure and Arterial Function in Rheumatoid Arthritis

Patients with rheumatoid arthritis have an increased risk of stroke and heart attack when compared to the rest of the population. Recent studies have shown that methotrexate, a disease-modifying antirheumatic drug (DMARDs) commonly prescribed for rheumatoid arthritis, reduces this risk. However, the mechanisms responsible for the protective effects of methotrexate on the heart and the brain are unknown.

The investigators have recently completed an observational study in participants with rheumatoid arthritis treated with either methotrexate or with other DMARDs. Participants on methotrexate had lower blood pressure and 'healthier' blood vessels than participants treated with other DMARDs. These differences were maintained over a period of 8 months. These results suggest that methotrexate lowers blood pressure and exerts salutary effects on blood vessels, which might explain the reduced risk of stroke and heart attack with this drug. However, the observational nature of this study does not allow establishing a clear cause-effect relationship between methotrexate treatment and the observed changes in blood pressure and blood vessels.

In order to address this issue, the investigators will recruit participants that have been recently diagnosed with rheumatoid arthritis and are about to start treatment with either methotrexate (Group 1) or another DMARD (Group 2). Then, the investigators will assess their blood pressure and blood vessels for 6 months. The investigators will use an injectable (subcutaneous) form of methotrexate because this might provide better effects on blood pressure and blood vessels. The investigators will also study a third group (Group 3) of rheumatoid arthritis participants already on treatment (\> 1 year) with oral methotrexate, with or without other DMARDs. They will be switched to subcutaneous methotrexate, but continuing all their other medications, for 6 months to see whether the subcutaneous form can further reduce blood pressure and provide additional salutary effects on blood vessels. Finally, the investigators will study a fourth group (Group 4) of participants with rheumatoid arthritis already on treatment (\> 1 year) with DMADRs other than methotrexate who will continue with the same medications for 6 months, to assess possible fluctuations in blood pressure and blood vessel markers over time.

Each participant will attend three study visits (baseline, 1 and 6 months), each lasting between 60 and 90 min.