Background Rheumatoid arthritis (RA) requires multiple drug regimens, because of its chronic, progressive disease nature. Drug adherence is defined as patients take medications as prescribed. Previous studies have reported that adherence of RA patients was about 30% to 80%. However, factors affecting nonadherence has not been well documented.
Objectives The current study aimed to assess adherence in RA patients and to identify risk factors for nonadherence.
Methods Rheumatoid arthritis patients over the age 18 who satisfied the 1987 ACR criteria were included from the KORean Observational study Network for Arthritis (KORONA). We selected 3,523 patients who answered the self-report questionnaire at enrollment. We classified patients into two groups. Patients who failed to take their medications for more than 5 days in total over the preceding 60 days were included in the nonadherence group and their reasons for nonadherence was investigated. T-test and Chi-square were used to compare two groups and logistic regression was used to identify risk factors.
Results The adherence rate was 90.4% (3,184 out of 3,523 patients). The reasons for nonadherence were: forgetfulness (36.9%), feeling asymptomatic (23.3%), side effects (12.4%), and taking alternative treatment (10.3%). Nonadherence patients were younger (50.9 years vs. 54.6 years, p≤0.01), reported side effects (44.2% vs. 33.3%, p≤0.01) and had lower Health Assessment Questionnaire (HAQ) score (0.57 vs. 0.68, p<0.01). Multivariate analyses were performed to identify the risk factors for nonadherence (n=3,094). It showed that young age (OR =1.02, 95% CI 1.01 to 1.03), having experience of side effects (OR=1.82, 95% CI 1.41 to 2.34) and lower HAQ score (OR=1.48, 95% CI 1.13 to 1.90) were associated with nonadherence. We did subgroup analysis to identify risk factors for nonadherence due to forgetfulness, young age (OR=1.04, 95% CI 1.02 to 1.06), having experience of side effects (OR=1.72, 95% CI 1.14 to 2.60) and low HAQ score (OR=1.80, 95% CI 1.12 to 2.89) were found to be also associated with forgetfulness.
Conclusions In this study, relatively low proportion of 9.6% of the RA patients showed nonadherence. The major reason of nonadherence was forgetfulness. Young age, experience of drug side effects, and low HAQ score were commonly associated with nonadherence and forgetfulness. To improve adherence for RA treatment, further studies for impact of adherence and patient-physician communication on improving outcomes of RA should be conducted.
Acknowledgements This study was supported by a grant of the Korea Healthcare technology R&D Project, Ministry of Health and Welfare, Republic of Korea (HI10C2020).
Disclosure of Interest None declared