Abstract
Objective
To examine whether dose escalation of intramuscular (IM) methotrexate (MTX) up to 45 mg/week improves disease control in patients who have active rheumatoid arthritis (RA) despite receiving conventional doses (15 mg/week) of IM MTX, and to obtain preliminary data on patient tolerability and adverse effects of higher doses of IM MTX.
Methods
Patients >18 years of age who had active RA, defined as a European League Against Rheumatism (EULAR) Disease Activity Score in 28 joints (DAS28) of >3.2, and who had received 15โ20 mg/week of oral MTX for at least 2 months were switched (week 0) to 15 mg/week of IM MTX for 6 weeks. Patients whose DAS28 remained >3.2 at both week 4 and week 6 were randomized, in a doubleโblind manner, either to continue to receive 15 mg/week IM MTX with monthly placebo escalation or to receive escalating doses of IM MTX monthly up to 45 mg/week. The dose of MTX or placebo was escalated every 4 weeks if the DAS28 was >2.5. Safety assessments and determination of the DAS28 were performed every 2 weeks and monthly, respectively. Disease activity parameters from the American College of Rheumatology (ACR) core disease activity set and health status as recorded on the Medical Outcomes Study ShortโForm 12 were determined at baseline (week 0) and final assessment (week 22). The primary outcome was the percentage of patients in each group achieving a target DAS28 of <3.2. Secondary outcomes comprised the percentage of patients whose DAS28 improved by >1.2, the percentage of patients achieving a 20% improvement in the ACR core disease activity measures (ACR20), and the percentage of patients achieving a good response, a moderate response, or no response in accordance with the EULAR response criteria.
Results
Sixtyโfour patients were eligible for entry and were switched from oral MTX to 15 mg/week IM MTX. At baseline, the mean ยฑ SD DAS28 was 5.6 ยฑ 0.88; after 6 weeks of IM MTX, the DAS28 had improved by a mean of 0.42 (95% confidence interval [95% CI] 0.15โ0.69). At 6 weeks, 54 patients still had a DAS28 of >3.2 and were therefore eligible for randomization. By 22 weeks, 1 patient (3.7%) in each group achieved the primary outcome of a DAS28 <3.2 (95% CI for the difference between the groups โ15% to +15%). Five patients (18.5%) in each group showed an improvement of >1.2 in the DAS28 (95% CI for the difference between the groups โ18% to +18%). One patient (3.7%) in each group achieved an ACR20 response, but none achieved a good response as defined by the EULAR response criteria. One patient in each group had a serious adverse reaction; minor adverse reactions were more frequently reported in the dose escalation group.
Conclusion
Switching from oral to parenteral MTX 15 mg/week results in a minor improvement in disease control. For patients with active RA receiving 15 mg/week IM MTX, increasing the dose up to 45 mg/week does not improve disease control. Higher doses of IM MTX were generally well tolerated and not associated with an increase in serious adverse reactions to the drug.