Background/Purpose:

Methotrexate (MTX) is the most commonly used medication in rheumatoid arthritis (RA), although use of oral and subcutaneous (SQ) preparations in real-world settings has not been well characterized.

Methods:

Using national data from a large commercially insured population in the U.S. from 2005-2011, we identified RA patients (pts) on the basis of 2 RA diagnosis codes initiating oral MTX (no prior use ever, minimum of 6m clean period) who also had no prior use of hydroxychloroquine (HCQ), sulfasalazine (SSZ), leflunomide (LEF) or biologic use and had at least one year of follow-up available. Subsequent dose escalation of oral MTX or switch to SQ MTX, HCQ, SSZ, and LEF were characterized. Subsequent use and timing of addition of biologics was examined for those had at least one switch, adjusting for multiple potential confounders using Cox proportional hazards models with switch date as time zero.

Results:

New oral MTX users (n=4,048) were 74.2% women, had mean +- SD age of 51.1+- 11.9 years and contributed a median (IQR) follow-up of 2.4 (1.6, 3.6) years; 28.1% never changed dose of oral MTX and remained at their starting dose; common doses included 10.0 mg/week (24.9%) and 15.0mg/week (26.3%). Of all patients, only 48.2% used oral MTX at >= 20mg/week at any time. Overall, 73.8% stayed on oral MTX (with or without dose increase) and did not add or switch to HCQ, SSZ, LEF, or SQ MTX. The remainder switched or added HCQ (14.0%), SSZ (6.2%), LEF (9.5%) or switched to SQ MTX (2.9%). The median (IQR) dose of oral MTX prior to switch to SQ was 15.0 (15.0, 20.0) mg/week and occurred at a median (IQR) of 322 (146,527) days.

Overall, 35.3% of the cohort subsequently initiated a biologic, mostly (90.3%) anti-TNF therapy. Of these individuals, 46.0% never used MTX at a dose of >= 20mg; 21.9% never used MTX at a dose of >= 15mg.  Among pts who used biologics after switch to SQ MTX, the median (IQR) interval of time between switching to SQ MTX and initiation of a biologic was 113 (65, 233) days. Among patients who increased dose or switched to SQ MTX or other nbDMARDs, (n=2,685) and after multivariable adjustment, there were no significant differences in subsequent biologic initiation between patients who switched to SQ MTX vs. added or switched to SSZ , LEF or HCQ.

Conclusion:

Titration to higher doses of oral MTX and use of SQ MTX preparations among RA patients is uncommon, even for patients who subsequently used biologics. Further work to optimize MTX in RA is warranted.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/use-of-oral-and-subcutaneous-mtx-in-a-commercially-insured-rheumatoid-arthritis-population/