Comparison of claims vs patient-reported adherence measures and associated outcomes among patients with nonvalvular atrial fibrillation using oral anticoagulant therapy

Abstract

Objective: To compare oral anticoagulant (OAC) adherence among patients with nonvalvular atrial fibrillation (NVAF) using patient-reported and claims-based measures, and to evaluate the effect of OAC adherence on health care costs and patient satisfaction with OAC therapy.

Methods: This was a hybrid US observational study consisting of a longitudinal cohort survey followed by linkage and analysis of respondents' administrative claims data. Patients with NVAF receiving warfarin, dabigatran, rivaroxaban, or apixaban completed an initial survey and follow-up surveys at 4, 8, and 12 months. Patient-reported adherence was measured at each survey by Morisky Medication Adherence Scale (MMAS-8) and pharmacy claims-determined adherence by the proportion of days covered (PDC) for the 12-month period following the initial survey date; adherence was defined as MMAS-8 score =8 and PDC ≥80%. Patient satisfaction with OAC therapy was assessed by the Duke Anticoagulation Satisfaction Scale (DASS).

Results: Overall, 675 patients completed at least the initial survey (warfarin, n=271; dabigatran, n=266; rivaroxaban, n=128; apixaban, n=10). Fewer than half (47.9%) were PDC adherent, 37.2% were MMAS-8 adherent, and 19.4% were adherent by both measures. Total medical costs of PDC-adherent patients were significantly lower vs PDC-nonadherent patients (US$640 vs $993 per-patient per-month, respectively, p<0.05). MMAS-8-adherent patients reported higher treatment satisfaction; total DASS score was significantly lower among MMAS-8-adherent than MMAS-8-nonadherent patients (37.3 vs 42.9, respectively, p<0.001).

Conclusion: Using claims-based or patient-reported methods to measure OAC adherence may lead to different results when assessing impact on health care costs and satisfaction with anticoagulation medication. These results underscore the importance of considering both claims-based and patient-reported measures when evaluating treatment adherence in real-world settings.

Keywords: OAC; adherence; atrial fibrillation; health care costs.

Figure 1

Overall study design diagram. Abbreviation: HIRD, HealthCore Integrated Research Database.

Figure 2

All-cause health care resource utilization^a between adherent and nonadherent patients using PDC calculated from claims for the 12-month period including and after the initial survey. Notes: ^aUnadjusted results; *p<0.05; PDC_Adherent n=323, PDC_Nonadherent n=352. Abbreviations: PDC, proportion of days covered; INP, inpatient; ER, emergency room.

Figure 3

All-cause health care resource utilization^a between adherent and nonadherent patients using mean MMAS-8 scores determined from patient self-report for the 12-month period including and after the initial survey. Notes: ^aUnadjusted results; *p<0.05; MMAS_Adherent n=251, MMAS_Nonadherent n=424. Use of the ©MMAS is protected by US copyright laws. Permission for use is required. A license agreement is available from: Donald E Morisky, ScD, ScM, MSPH, Professor, Department of Community Health Sciences, UCLA School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095-1772, USA. Abbreviations: MMAS-8, Morisky Medication Adherence Scale 8-item; INP, inpatient; ER, emergency room.

Figure 4

Comparison of all-cause, stroke-related, and bleeding-related total medical costs^a between adherent and nonadherent patients using PDC calculated from claims for the 12-month period including and after the initial survey. Notes: ^aUnadjusted results; *p<0.05; PDC_Adherent n=323, PDC_Nonadherent n=352. Abbreviation: PDC, proportion of days covered.

Figure 5

Comparison of all-cause, stroke-related, and bleeding-related total medical costs^a between adherent and nonadherent patients using mean MMAS-8 scores determined from patient self-report for the 12-month period including and following the initial survey. Notes: ^aUnadjusted results; MMAS_Adherent n=251, MMAS_Nonadherent n=424. Use of the ©MMAS is protected by US copyright laws. Permission for use is required. A license agreement is available from: Donald E Morisky, ScD, ScM, MSPH, Professor, Department of Community Health Sciences, UCLA School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095-1772, USA. Abbreviation: MMAS-8, Morisky Medication Adherence Scale 8-item.

Figure 6

Comparison of all-cause total medical costs by type of services between adherent and nonadherent patients using PDC and mean overall MMAS-8 scores for the 12-month period including and following the initial survey. Notes: *p<0.05 vs nonadherent PDC cohort; PDC_Adherent n=323, PDC_Nonadherent n=352, MMAS_Adherent n=251, MMAS_Nonadherent n=424. Use of the ©MMAS is protected by US copyright laws. Permission for use is required. A license agreement is available from: Donald E Morisky, ScD, ScM, MSPH, Professor, Department of Community Health Sciences, UCLA School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095-1772, USA. Abbreviations: PDC, proportion of days covered; MMAS-8, Morisky Medication Adherence Scale 8-item.

Figure 7

Comparison of Duke Anticoagulation Satisfaction Scale (DASS) mean scores between adherent and nonadherent patients using PDC and mean overall MMAS-8 scores for the 12-month period including and following the initial survey. Notes: *p<0.05 vs MMAS nonadherent cohort; PDC_Adherent n=323, PDC_Nonadherent n=352, MMAS_Adherent n=251, MMAS_Nonadherent n=424. Use of the ©MMAS is protected by US copyright laws. Permission for use is required. A license agreement is available from: Donald E Morisky, ScD, ScM, MSPH, Professor, Department of Community Health Sciences, UCLA School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095-1772, USA. Abbreviations: PDC, proportion of days covered; MMAS-8, Morisky Medication Adherence Scale 8-item.