medwireNews: Around a quarter of patients with rheumatoid arthritis (RA) do not adhere to methotrexate treatment, shows a study based on electronic medication monitoring data.
Kaleb Michaud, from the University of Nebraska Medical Center in Omaha, USA, and co-investigators also identified a number of factors that may be associated with non-adherence, including disability and previous DMARD use.
The study included 60 patients with RA from 54 different US clinics who had been receiving oral methotrexate, either as monotherapy or in combination with biologics and conventional DMARDs, for up to 12 months.
Methotrexate use was measured by the Medication Event Monitoring System (MEMS) over 24 weeks. This system electronically registers when the cap is removed from a medication bottle and assumes that the prescribed dose is taken each time the bottle is opened. Opening of the bottle for refills or other reasons was recorded in patient diaries.
The researchers report in ACR Open Rheumatology that, at 24 weeks, methotrexate adherence, defined as the mean percentage of weekly correct dosing, was 74.8%, while underdosing was 21.2% and early dosing was 4.0%.
Adjusted regression analyses showed that the likelihood of full adherence was significantly lower among patients who were employed (odds ratio [OR]=0.82), those who had previously used a conventional DMARD other than methotrexate (OR=0.84), or those who had a higher level of disability according to the health assessment questionnaire (HAQ)-II (OR=0.77 per unit of HAQ disability) relative to those who were unemployed, were DMARD-naïve, or had a lower level of disability, respectively.
Conversely, the likelihood of full adherence significantly increased with increasing patient global assessment (PtGA) of disease activity (OR=1.05 per point).
The team also found that older age, being in employment, greater disability, less pain, and prior use of conventional DMARDs, and longer time on methotrexate were associated with an increased likelihood of underdosing.
And non-White ethnicity, lower PtGA, fatigue, greater patient belief that drugs were overused by physicians, and weaker beliefs about the specific necessity of the drug were each significantly associated with early dosing.
During the study, 17% of patients discontinued methotrexate. Older age and being in employment were both significantly associated with treatment discontinuation.
Michaud et al note that there were no significant differences in either adherence or persistence among patients receiving methotrexate monotherapy versus those receiving it in combination with other drugs, nor were there any differences between patients who had previously used biologics and those who had not.
The authors conclude that their findings suggest that there is “a need for screening and alternative treatment opportunities in nonadherent [methotrexate] patients with RA.”
They add: “Further research to advance understanding in this area will be helpful to identify and address barriers to optimal adherence.”
By Laura Cowen
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