Background/Purpose: Adherence to disease modifying anti-rheumatic drug (DMARD) therapy is suboptimal in patients with rheumatoid arthritis (RA). Efficient, low-cost measures are required for better monitoring of medication adherence in the rheumatology clinic. Self-report tools are the most efficient and cost-effective measures available. A 5-item version of the Compliance Questionnaire Rheumatology (CQR5) was developed from the original 19-item version to reduce patient burden. Long-term reliability (stability) of this questionnaire has not yet been evaluated over a period equivalent to RA patient follow-up (3 to 6 months). Therefore, we looked at stability of the CQR5 and the 9-item Medication Adherence Report Scale (MARS9), another short medication adherence tool that has been shown to be valid in a sample of RA patients.

Methods: RA patients (disease duration ≥ 1 year) taking at least one DMARD prescription were randomly selected from a rheumatology outpatient clinic database. Patients were assessed at baseline and three months. Demographic data were collected at baseline. At each visit, medication adherence was assessed with the CQR5 and MARS9. Each item on the CQR5 was scored on a four point Likert scale (1 = strongly disagree, 4 = strongly agree). Scores for each item were then summed into a total score which varied between 0 and 20. For the MARS9, each item was scored on a five point Likert scale (1 = always, 5 = never) and item scores were summed into a total score varying from 9 to 45. On both questionnaires, higher scores indicated greater adherence. Stability analysis was performed with the intraclass correlation coefficient (ICC) and the mean difference between measurements obtained at baseline and three months.

Results: 100 RA patients, ages [mean(SD)] 60.75(12.67) years, were recruited. 4 patients dropped out, therefore 96 were included in the analysis. In this sample, the CQR5 and MARS9 demonstrated good and fair stability, respectively [ICC_CQR5 = 0.73(CI_95% = 0.61 to 0.81); ICC_MARS9 = 0.43(CI_95% = 0.24 to 0.58)]. One-sample t-tests showed that the differences in measurement from baseline to three months were not significantly different from zero (p > 0.05) for both the CQR5 [mean(SD) = -0.22 (1.57)] and MARS9 [mean(SD) = -0.15 (4.18)]. The CQR5 and MARS9 had similar mean differences but variability for the MARS9 was larger than for the CQR5, indicating greater consistency across measurements for the CQR5.

Conclusion: We demonstrated stability of a short, rheumatology-specific adherence questionnaire in a time frame similar to RA patient follow-up. Our results also suggest that the CQR5 may be a more stable measure of medication adherence than the MARS9 when it is used in a rheumatology clinic setting.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/stability-of-two-short-medication-adherence-questionnaires-over-time-for-follow-up-in-patients-with-rheumatoid-arthritis/