Osteoporosis causes fragile bones which have an increased fracture risk and is a major public health concern. One osteoporotic treatment method is the use of bisphosphonates. However, this present study has highlighted that oral bisphosphonate treatments are associated with poor implementation and low adherence levels, leading to overall reduction in their effectiveness.

The study explains that drug adherence can be described as a process with three components:
Initiation – starting the treatment
Persistence – continuing to administer treatment
Implementation – taking treatment in accordance with dosing regimen

Generic drugs offer the opportunity to reduce healthcare costs. Such products receive marketing authorization based on bioequivalence to a reference product. However, it is noted that, in some cases they have been shown to have greater bio-adhesive properties to reference products which may possibly have direct tolerance effects as they may increase upper gastrointestinal tract irritation and ulceration risk.
If a generic has less tolerability, this can lead to reduced adherence which has been demonstrated in several studies.

In light of this, the authors carried out an analysis of the French national database to examine the adherence levels with both brand and generic bisphosphonates. The data were collected from the Generalist Sample of Beneficiaries between 2009–2015. This showed that 43,633 patients that were 50 or over had a reimbursement for oral bisphosphonate. Among them 6,612 patients initiated an oral bisphosphonate osteoporosis treatment osteoporosis – 2,193 (33.2%) with brand bisphosphonate, 1,710 (25.9%) with generic bisphosphonate, and 2,709 (41.0%) with bisphosphonate associated with vitamin D.

Over the 7-year period of the study initiation with brand bisphosphonates decreased (from nearly 60% to less than 10%) while that with generic bisphosphonates increased (from less than 10% to nearly 50%). It was seen that a small proportion of patients switched to different bisphosphonates during the first 12 months after initiation – these were not included in further analysis.

Treatment persistence
When it came to the 1,834 patients taking brand phosphonates, it was found that, after 12 months, only 537 remained on first-line bisphosphonate. The majority (over 70%) of patients discontinued use during this time (and 0.3% died). For the 1,495 patients on generic bisphosphonates, only 458 remained taking the treatment after the first year, with 69% discontinuing treatment (0.4% died). In both cases, the six-month persistence was approximately 40%.

Treatment implementation
One thousand three hundred and sixty-four patients undertook first-line bisphosphonate treatment that lasted six months. For the brand and generic drug product the mean duration was 334 days (±57) vs 331 days (±59), respectively. The authors also calculated that the rate of good implementation was 76.2% and 78.1%, respectively. Their analysis also revealed that initiating oral bisphosphonate treatment with brand was associated with a higher risk of discontinuation within 12 months. The risk of good implementation was significantly lower for those taking brand bisphosphonates.

Discussion
The study results did not uncover any evidence that there was lower adherence to generic bisphosphonates as compared to brand products. In fact, it was seen that there were higher persistence rates and better implementation for generic products after a year of treatment.

The authors note that their results differ to those of other published studies. They suggest that reasons for this may relate to differences in patient’s selection, study period, oral bisphosphonate molecules studied, designs of the studies, or use of propensity scores. In addition, they note that the previous comparative studies were carried out before 2012 and now generic treatment options are better accepted by patients and physicians. Their study also shows a connection between treatment and 1-year persistence, which was integrated in analysis. This was not done in previous studies. The authors also note that in France in 2009, regulation implementation meant that patients requesting brand-name products were required to personally pay for this treatment option, whereas generics were covered by health insurance. It is thus suggested that this financial factor may have led to reduced adherence of the brand bisphosphonates. In addition, the authors suggest that physicians may be inclined to prescribe generics to patients who are likely to be more adherent, and brand bisphosphonate to patients likely to be less adherent.

Overall, the study brings an up-to-date view of adherence levels of brand name versus generic bisphosphonates for osteoporosis treatment, using a large dataset over a period of seven years, and comprehensive analysis methods.

Conflict of interest
The authors declared that the research [1] did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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Reference
1. Viprey M, Xue Y, Rousseau A, et al. Adherence with brand versus generic bisphosphonates among osteoporosis patients: a new-user cohort study in the French National Healthcare Insurance database. Sci Rep. 2020;10(1):7446.

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