Background/Purpose: Bisphosphonates (BPs) have been widely used for the treatment and prevention of osteoporosis for two decades. Although new parenteral preparations have been introduced, oral BPs still represent the vast majority of osteoporosis treatments. Little is known about the characteristics of or regional differences in long-term oral BP users.

Methods: We evaluated the long-term use of oral BPs in the national US Medicare and Ontario (ON) Canada data systems. The US Medicare cohort consisted of women aged ≥65 years with an osteoporosis or fracture diagnosis code, or BP prescription fill. The ON data consisted of women aged ≥66 years who were new users of oral BPs. We identified women with three years of continuous medical and pharmacy coverage. Long-term BP users were those with exposure to an oral BP (alendronate, risedronate, ibandronate, and etidronate) in each of the three most recent years of available data (2009-2011). We evaluated demographic and BP utilization data including, BP exclusivity (no exposure to another BP agent in three year period) and compliance to therapy using proportion of days covered (PDC) (days of drug supplied in 3 years/3*365.25) . Users with a PDC of ≥70% were considered compliant. 

Results: We identified 888,704 US and 99,530 ON women meeting the inclusion criteria with at least one oral BP prescription in the most recent data. We then identified 698,012 US and 54,656 ON long-term oral BPs users (Table). Alendronate was primarily used by Medicare patients (78.0%), whereas risedronate was the primary oral BP in ON (56%). Based on the available data, the mean duration of us among the long-term BP users was five years in both US (SD: 1.1) and ON (SD: 2.2). In the US, risedronate users were more likely to be exclusive users (83%) compared to alendronate users; whereas in ON, a higher proportion of alendronate users were considered exclusive users than risedronate users. All ibandronate users were exclusive users in US data. Compliance was higher in ON (80% alendronate, 78% risedronate) than in US (63% alendronate, 63% risedronate).

Conclusion:  Although alternative preparations of BPs and new non-BP drugs have emerged in the market, the prevalence of oral BP use is high. In the data evaluated, the prevalence of long-term use (≥3years), was also high in both countries. However, compliance differed by country. Evaluations in more recent data would determine if and how drug holidays have altered these characteristics.

Table. Characteristics of Long-term Oral Bisphosphonate Users

	US, 2009-2011 (n=698,012)	ON, 2009-2011 (n=54,656)
Age, mean (SD)	79.3 (7.4)	74.0 (6.4)
Mean BP durationa, yrs (SD)	5.0 (1.1)	4.9 (2.2)
Most recent BP, (n,%) Alendronate Risedronate Ibandronate	544,656 (78.0) 96,795 (13.9) 56,561 (8.1)	24,056 (44.0) 30,600 (56.0) –
Exclusive BP usersb, (n,%) Alendronate Risedronate Ibandronate	419,496 (77.2) 80,314 (83.0) 56,561 (100.0)	22,596 (93.9) 26,981 (88.2) –
Compliant BP usersc, (n,%) Alendronate Risedronate Ibandronate	262,125 (62.5) 50,880 (63.4) 33,981 (60.1)	18,173 (80.4) 20,981 (77.8) –

^aMean duration based on first BP dispensed in each data system. US = 2006-2011; ON: 2002-2011

^bExclusive users are those who only filled a prescription for each oral BP among most recent BP users

^cCompliance estimated at proportion of days covered (PDC) of ≥70% among exclusive BP users

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-oral-bisphosphonate-use-for-osteoporosis-among-older-women-us-and-canadian-perspective/