Adherence to combination DMARD therapy and treatment outcomes in rheumatoid arthritis: a longitudinal study of new and existing DMARD users.
Medication adherence is believed to be a major contributor to treatment outcomes yet studies quantifying this relationship as rare in rheumatoid arthritis (RA). To determine the association of adherence to DMARD therapy with treatment outcomes among new and existing DMARD users over 2 years. Relevant clinical parameters were obtained from a longitudinal cohort of RA patients, most of who were treated with combination therapy. Patients were classified as adherent if the proportion of days covered for each DMARD was ≥80%. Outcome measures were the change in the disease activity score in 28 joints (DAS28), simplified disease activity index (SDAI), modified health assessment questionnaires (mHAQ) and proportion of patients who achieved response criteria. An inverse propensity-score weighting method was used to estimate the association of adherence with each outcome. Of 194 patients invited, a total of 111 patients (new = 45 and existing = 66 DMARD users) met study eligibility. DMARD-naive patients demonstrated relatively higher rates of adherence compared to existing users. After controlling for confounding variables, adherence was significantly associated with reduction in DAS28 (β = -1.5, 95% CI of β = - 2.17 to -0.83, p < 0.0001), SDAI (β = -9.44, 95% CI of β = -15.53 to -3.35, p = 0.002) and mHAQ (β = -0.269, 95% CI of β, -0.462 to -0.077, p = 0.017) over 2 years among new patients and adherent patients were more likely to achieve most response criteria compared to non-adherent patients. Such associations were not replicated among existing DMARD users. Adherence to combination DMARD therapy was associated with improvements in disease activity and functional outcomes in the first 2 years of therapy.
School of Pharmacy and Medical Sciences and Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide, SA, 5001, Australia. wabnt001@mymail.unisa.edu.au.
Nasir
N
Wabe
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia.
Anita
A
Lee
Rheumatology Unit, Repatriation General Hospital, Daw Park, SA, 5041, Australia.
Mihir
M
Wechalekar
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia.
Leah
L
McWilliams
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia.
Susanna
S
Proudman
School of Pharmacy and Medical Sciences and Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide, SA, 5001, Australia.
Michael
M
Wiese
D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D004359:Drug Therapy, Combination; D006801:Humans; D008137:Longitudinal Studies; D055118:Medication Adherence; D008875:Middle Aged; D020127:Recovery of Function; D012074:Remission Induction; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome
D018501:Antirheumatic Agents
Clinical outcomes; Medication adherence; Propensity scores; Rheumatoid arthritis; Treatment outcomes