Background/Purpose:

Given alendronate’s (ALN) prolonged skeletal retention and emerging safety concerns, the ASBMR task force recommended consideration of a “drug holiday” after 5 years of use. Distinguishing a prolonged gap in intended treatment vs. an intentional drug holiday is often unclear. We sought to estimate the prevalence of potential ALN holidays using two definitions of drug discontinuation, and to evaluate the characteristics of those who restart osteoporosis (OP) therapy after an ALN treatment gap.

Methods:

We included only women ALN users (n = 81,287) with a treatment gap in the 2006-2015 US Medicare data, with medical and pharmacy coverage (Medicare parts A, B, and D), and who were at least 80% adherent (MPR) with ALN for ≥3 years prior to the gap. We excluded patients with history of cancer, Pagets, Osteogenesis Imperfecta, or systemic hormone therapy. We evaluated the proportion of women with a treatment gap (no prescription claims) for ≥ 6 months and/or ≥ 1 year at which time follow-up began (day 184 and day 366) (index date) until restarting of any OP medication (study end). We used descriptive statistics to characterize women restarting vs. not restarting therapy after a gap of ≥1 year.

Results:

Using the 6-month gap definition, we identified 35,239 women (43.3% of previously adherent long-term ALN users) who discontinued ALN, of which 6172 (17.5%) restarted on any OP therapy. The median time to restart was 162 days (58, 413.5; 25^th and 75^th percentile). Half (50%) of the women restarted therapy within a year of stopping, suggesting that a 6-month gap may not truly represent an intended drug holiday. Using a ≥1 year gap definition, we identified 27,436 (33.8%) women with a possible drug holiday, of which 2978 (10.9%) restarted OP therapy. The median time to restart was 259 days (92, 512; 25th and 75th percentile). Using the ≥1 year definition, restarters and non-restarters differed significantly (p < 0.001) by fracture history (6.9% vs 5.1%), history of previous DXA (21.6% vs. 15.0%), and ≥1 rheumatologist or endocrinologist visit (13.8% vs. 8.6%).

Conclusion:

Given the large proportion of rapid restarters, a drug holiday gap of only 6-months may not accurately reflect a true drug holiday; a minimum of a 1-year gap appeared more appropriate for defining a likely drug holiday. Increased OP care and history of fractures were associated with OP therapy restart.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/defining-alendronate-drug-holidays-and-re-initiation-in-us-medicare-data/