Session Information
Date: Sunday, November 5, 2017
Title: Plenary Session I
Session Type: ACR Plenary Session
Session Time: 11:00AM-12:30PM
Background/Purpose: Given FDA warnings, drug holidays (temporary or permanent discontinuation) of bisphosphonates (BPs) after long-term (3-5 years) continuous therapy is becoming increasingly common in the United States (US). However, the benefits and risks of stopping BPs, and the optimal timing to restart, remain unclear. We conducted a population-based cohort study of women on long term BP therapy to evaluate the rate of hip fracture following a drug holiday.
Methods: We used Medicare data (2006-2014) to identify all women with medical and pharmacy coverage who initiated a BP and were at least 80% adherent for ≥3 years (‘baseline’), at which follow-up time began. Patients using other bone therapies (e.g. denosumab, estrogen, teriparatide, calcitonin) were excluded or censored if they started after follow-up began. We calculated crude rates of hip fracture for continuing BP therapy and among those who discontinued, for categories of time since discontinuing (i.e., length of drug holiday), extending up to 3 years. We used Cox proportional hazards models to evaluate the risk of discontinuing per the length of the drug holiday, using age as the time axis and controlling for potentially confounding factors, with and without adjusting for death as a competing risk.
Results: We identified 156,236 women who were highly adherent, long-term BP users. The mean (SD) age was 78.5 (7.5) years. The most commonly used BPs were alendronate (71.7% ever use, 52% exclusive use) and zoledronic acid (16.2% ever use, 8.9% exclusive use). During a median (IQR) follow up of 2.1 (1.0, 3.3) years, 62,676 (40.1%) of women stopped BP therapy for at least 6 months or more. Among these women, 7,947 (12.7%) subsequently restarted any BP. Overall, 16,904 (10.8 %) died.
A total of 3,745 hip fractures occurred during follow-up. Hip fracture rates were lowest among women who were current users, and gradually increased as the length of the drug holiday increased, achieving their maximum with a drug holiday >2 years (Table).
Conclusion: In a large cohort of U.S. women, a BP drug holiday greater than 2 years was associated with a significantly increased risk for hip fracture of up to 39% compared to continued BP use.
Table: Hip fracture Rate By Duration of BP Drug Holiday, Adjusting for Competing Risk of Death
|
Time since Bisphosphonate Discontinuation (yrs) |
Number of hip fractures, n |
Crude Incidence Rate per 1,000 person-years |
Adjusted* Hazard Ratio |
|
0 (i.e. current use) |
1958 |
9.6 (9.2, 10.1) |
1.0 (reference) |
|
>0 to <= 3 months |
530 |
13.1 (12.0, 14.3) |
1.29 (1.17, 1.42) |
|
>3 months <=1 year |
539 |
12.0 (11.0, 13.1) |
1.12 (1.02, 1.24) |
|
>1 to <=2 years |
422 |
13.3 (12.0, 14.6) |
1.21 (1.09, 1.35) |
|
>2 to <=3 years |
235 |
15.7 (13.7, 17.8) |
1.39(1.21, 1.59) |
|
*adjusted for age, region, race, rural or urban, median income, calendar year, comorbidity(fragility fracture, charlson comorbidity index score), DXA, number of physician visits, care by a rheumatologist or endocrinologist, long term care residence, vitamin D deficiency, glucocorticoids, and proton pump inhibitors |
|||
To cite this abstract in AMA style:
Curtis JR, Chen R, Li Z, Arora T, Saag K, Wright NC, Daigle S, Kilgore M, Delzell E. The Impact of the Duration of Bisphosphonate Drug Holidays on Hip Fracture Rates [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/the-impact-of-the-duration-of-bisphosphonate-drug-holidays-on-hip-fracture-rates/. Accessed .« Back to 2017 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-impact-of-the-duration-of-bisphosphonate-drug-holidays-on-hip-fracture-rates/