Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Measuring Therapeutic Adherence in Rheumatoid Arthritis (RA) Using a Medication Event Monitoring System (MEMS).

A. Waimann,  Christian, F. Marengo,  Maria, de Achaval,  Sofia, L. Cox,  Vanessa, Garcia Gonzalez,  Araceli, N. Richardson,  Marsha, E. Suarez-Almazor,  Maria

Background:

Treatment adherence is an important aspect in RA. Multiple methods of measuring adherence have been proposed, with electronic monitoring considered one of the most accurate measures. The objective of our study was to electronically quantify adherence to oral disease modifying antirheumatic drugs (DMARDs) and prednisone in patients with RA.

Methods:

This study was part of a 2– year prospective cohort of 201 patients from 2 publicly-funded county hospitals, in which 110 patients agreed to have their RA drug therapies electronically monitored with MEMS® caps (AARDEX). These are medication bottle caps with a microchip that records the time and date of bottle openings. Adherence to daily medications was determined as the percentage of days with correct number of doses taken. Adherence to weekly methotrexate (MTX) was determined as the percentage of doses taken within an interval of 7 ± 1.75 days. We also estimated percentage of prescribed doses taken (not considering dosing interval). MEMS® data was downloaded with each refill. Patient outcomes were assessed at baseline, 3, 6, 12, 18 and 24 months including functional status, Disease Activity Index 28 (DAS28), SF-12, Medical Outcome Study social support (MOS), Center for Epidemiologic Studies Depression Scale 10 items (CDES-10) and sociodemographic variables. 91% of the patients completed 2 years follow-up; for the remainder we used the last observation for analysis. The statistical analysis was carried out using SAS.

Summary of Results:

86% were female, 67% Hispanic, and 21% African-American; mean age was 49y(±11), disease duration 7y(±5), DAS28 4.1(±1.4),MHAQ 1.8(±0.5); 47% received monotherapy, 39% two DMARDs, 12% three DMARDs and 56% biologics (not oral, therefore not electronically monitored). Adherence of 5 drugs was electronically monitored (table). Adherence for doses taken on schedule (day/wk) was 59% for DMARDs and 61% all drugs. Only 21(20%) of patients had an average adherence >= 80%. At 2 years, these patients showed better patient self-reported disease activity and pain by VAS (p<0.029; p<0.008). No differences were observed for DAS28. Percent prescribed doses taken was greater than % days or weeks with correct doses taken, especially for MTX, suggesting lack of adherence with appropriate prescribed intervals. Patients with self-reported worse global status by visual analogue scale (VAS), and those with better mental health by SF12 MCS were statistically more likely to be adherent (p<0.03; p<0.003). Patients living alone, and those separated or widowed were less adherent (p<0.008; p<0.003). Social support (MOS) showed a borderline positive correlation (r=0.18, p<0.06).

DrugNMean doseTotal days monitored% prescribed doses taken on schedule% prescribed doses taken
Methotrexate6916 mg/week479 (±244)56.1 (±24)121.8 (±78)
Leflunomide3617 mg/day389 (±266)69.1 (±18)80.7 (±17)
Hydroxychloroquine31243 mg/day494 (±256)58.5 (±22)75.8 (±21)
Sulfasalazine6891 mg/day394 (±344)50.5 (±27)73.0 (±28)
Prednisone586 mg/day437 (±274)65.1 (±20)79.1 (±30)
Average DMARDs10159.1 (±22)101.1 (±65)
Average all drugs11061.1 (±21)94.1 (±43)

Conclusion:

On average, RA patients showed 61% correct medication intake, with only 1 in 5 taking oral therapies as prescribed at least 80% of the times. Long-term cohort studies should evaluate the impact of non-adherence on RA outcomes.

To cite this abstract, please use the following information:
A. Waimann, Christian, F. Marengo, Maria, de Achaval, Sofia, L. Cox, Vanessa, Garcia Gonzalez, Araceli, N. Richardson, Marsha, et al; Measuring Therapeutic Adherence in Rheumatoid Arthritis (RA) Using a Medication Event Monitoring System (MEMS). [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1047
DOI: 10.1002/art.28814

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