Purpose: The purpose of this study was to perform a prescription gap analysis and evaluate the differences in observed versus recommended time to refill for patients receiving adalimumab or etanercept treatment.
Method: Patients aged ≥ 18 years, with ≥ 2 pre-index ICD-9 diagnosis codes for RA (714.xx), and with an index prescription claim for adalimumab or etanercept received between 1/1/2004-10/31/2009 were identified from the HealthCore Integrated Research database. Patients were continuously enrolled for 6 months pre- and 12 months post-index. Patients were required to have adalimumab or etanercept prescriptions at index and on or after the 365th day of follow-up. Patients were excluded if they had: any biologic use 6 months pre-index; switched to another biologic agent 12 months post-index; selected inflammatory conditions. Data were reported for 12 months post-index. A treatment gap was calculated for each sequence of refills as the difference in days between subsequent prescription refills (observed time to refill) minus the day’s supply of the previous prescription (recommended time to refill).
Result: A total of 1,902 RA patients receiving adalimumab (N=621) and etanercept (N=1,281) were identified. There were no significant differences in demographic and clinical characteristics (mean age 50 years, 76% female). Overall, patients refilled a mean/median of 10/11 prescriptions for both adalimumab and etanercept. Among patients with a gap in observed refill time that exceeded the recommended refill time, the mean differences (assessed at each individual refill period) ranged from 19 to 33 days for adalimumab and from 19 to 37 days for etanercept.
Conclusion: Gaps between observed and recommended times to refill were found among adalimumab and etanercept users during each refill period. Patient adherence with physician prescribing instructions should be monitored. The economic impact of lack of adherence with these drugs on the healthcare system requires additional research.
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