Background/Purpose: Medication nonadherence is common in SLE and leads to increased hospitalizations, morbidity, and mortality. To better recognize nonadherence and address adherence barriers, there is a need for a validated and easily implemented tool. Based on our prior mixed-methods results and literature review, we adapted the Domains of Subjective Extent of Nonadherence (DOSE- nonadherence) questionnaire, a previously validated (in patients with hypertension and hepatitis C) self-reported measure of extent of nonadherence and reasons for nonadherence, to better illuminate nonadherence in SLE. This study aimed to refine and assess the validity of the DOSE-nonadherence in the context of SLE.

Methods: We refined the DOSE-nonadherence questionnaire through cognitive interviewing with SLE patients recruited from an academic lupus clinic and feedback from six lupus clinic rheumatologists. The instrument was then administered to patients taking any oral SLE medications. To assess its validity, we compared the results of the refined DOSE-nonadherence questionnaire to the Beliefs about Medicines Questionnaire (BMQ), the Medication Adherence Self-Report Inventory (MASRI), an existing self-reported adherence, medication possession ratio (MPR) based on pharmacy refill data, and available HCQ blood levels.

Results: Sixteen patients (median age 43, 100% female, 50% Black) participated in cognitive debriefing interviews to refine the DOSE-nonadherence. The refined DOSE-nonadherence was administered to 99 patients (median age 50, 96% female, 42% Black, 33% < college education, 55% married or cohabiting, 51% < $50K annual household income, 44% on Medicaid/Medicare). Of these, 85% were prescribed HCQ, 31% MMF, 14% AZA, 12% MTX, 1% LEF, and 5% belimumab.

Forty-four percent of patients reported nonadherence based on the refined DOSE-nonadherence. The extent of nonadherence score was highly correlated with MASRI (r=0.60) and HCQ blood levels (r=-0.73) and moderately correlated with HCQ MPR (r=-0.48), demonstrating convergent validity. The correlation between extent of nonadherence and BMQ was small (r=-0.26-0.36), demonstrating discriminant validity (Table 1).

Nonadherent patients reported on average 3.5 [IQR 1-6] reasons for nonadherence. The most common reasons were busyness and forgetting (n=25), physical fatigue (n=19), pill fatigue (n=15), feeling well (n=12), irregular schedule (n=11), and noticing no difference when skipping a dose (n=10).

Conclusion: Our results support the validity of the DOSE-nonadherence in assessing extent and reasons for nonadherence among SLE patients. In comparison to the MASRI, the DOSE-nonadherence helps identify reasons for nonadherence. This instrument can be used to identify, rigorously study, and guide the development of interventions to target the most common reasons for nonadherence in SLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/validation-of-a-self-reported-measure-of-extent-and-reasons-for-nonadherence-in-sle/