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Arthritis
Volume 2015, Article ID 915142, 7 pages
http://dx.doi.org/10.1155/2015/915142
Research Article

Adherence to Methotrexate in Rheumatoid Arthritis: A Danish Nationwide Cohort Study

1The Parker Institute, Department of Rheumatology, Copenhagen University Hospital at Bispebjerg and Frederiksberg, 2000 Copenhagen F, Denmark
2Department of Health Science and Technology, Center for Sensory-Motor Interaction (SMI), Aalborg University, 9220 Aalborg, Denmark
3Aalborg University Hospital, Clinical Institute, 9100 Aalborg, Denmark
4Department of Rheumatology, Region Hospital, 8600 Silkeborg, Denmark
5Clinic of Rheumatology, 4000 Roskilde, Denmark
6Copenhagen Centre for Arthritis Research, Center for Rheumatology and Spine Diseases, Glostrup Hospital, 2600 Glostrup, Denmark
7Department of Rheumatology, Copenhagen University Hospital, 2900 Gentofte, Denmark
8Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University, Washington, DC 20057, USA
9Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark

Received 22 December 2014; Accepted 29 January 2015

Academic Editor: Shinichi Kawai

Copyright © 2015 Henning Bliddal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objectives. To study adherence to methotrexate (MTX) and factors of importance thereof in patients with rheumatoid arthritis (RA). Methods. Patients with a hospital diagnosis of RA (ICD10 codes M05.X or M06.X) after January 1, 1997, and aged ≥18 years at the date of first diagnosis/contact, with at least one prescription of MTX (L04AX03), were included. Results. A total of 18,703 (47.6%) patients had ever used MTX among 39,286 with a diagnosis of RA; among the MTX users, 16,503 (88.2%) had filed more than one MTX prescription. The median time from diagnosis to first MTX prescription was 0.66 (IQR 0.26–1.80) years. In those who filed more than one MTX prescription, the mean adherence time for ≥7.5 mg MTX per week was 1,925 (IQR 467–3,056) days for patients treated in private practice versus 1,892 (IQR 452–3,316) days for patients treated in hospital. The main determinants of nonadherence were female gender, younger age, and time from diagnosis to initiation of MTX. Conclusions. Treatment at hospital or in private practice did not influence the adherence to MTX. Nonmodifiable factors of importance were gender and age, while adherence to MTX therapy decreased with time lapse between diagnosis and prescription.