Background/Purpose

Individuals with osteoporosis (OP) have an increased susceptibility to fractures. Prevention and treatment of postmenopausal OP is critical to decreasing the risk of non-traumatic bone fractures. These fractures cause medical and personal hardships, particularly among older individuals, and are a burden on health care systems (Adachi 2003). The objective of this study was to quantify the number of osteoporotic women 55 years of age or older that remain at high risk of fracture despite benefits of prior oral bisphosphonate (BIS) therapy.

Methods

This study retrospectively analyzed a subset of participants in The Canadian Multicentre Osteoporosis Study (CaMos). CaMos is a prospective cohort study of 9,423 selected from community dwelling men and women older than 25 years of age. A subset of women from the CaMos dataset were studied who were 55 years of age or older with OP, who did not have Paget’s disease and who reported receiving BIS therapy for at least two consecutive years. Additionally, patients must have had at least three years of follow-up data from the index date (start of 2 years of BIS therapy), and be considered osteoporotic at baseline for inclusion. Patients with lumbar spine or hip BMD of < -2.5 at baseline, or with prior vertebral or hip fractures, were classified as osteoporotic. Two consecutive years of BIS therapy was utilized as a proxy for adherence to BIS therapy, and was based on annual self-reported patient questionnaire responses regarding BIS therapy. High risk for fracture was determined by the following three criteria: 1.) Fractures during the first year following the BIS treatment period. 2.) Any decline in BMD at the hip (femoral neck) or lumbar spine (L1-L4) from baseline BMD (the most recent BMD prior to the treatment period) to the “study BMD” (i.e. the closest BMD after the 2-year treatment period). 3.) A “study BMD” less than -2.5 at the hip (femoral neck) or lumbar (L1-L4) spine.  Descriptive analysis was conducted to characterize the fracture risk profile in this patient population.

Results

628 women with a mean age of 71.6 years met the eligibility criteria. 24 participants (3.8%) experienced fractures during the first year following the two consecutive years of BIS therapy. Of the 24 patients with fractures during this time, 3 had fractures during the two years of BIS therapy. Almost two thirds (59.2%) of participants (372) experienced a decline in BMD from baseline following two years of therapy. Additionally, 71.3% of patients (448) were classified as osteoporotic after two years of OP therapy.

Conclusion

This study demonstrates that despite the benefits of OP treatment with BIS, a considerable proportion of women represented in the CaMos database who reported taking oral BIS therapy for two years remained at high-risk for OP fractures. In light of this finding, alternative treatments should be considered for many osteoporotic women who remain at high risk for OP or non-traumatic fractures.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/osteoporotic-women-at-high-risk-for-fractures-despite-two-years-of-oral-bisphosphonate-therapy-analysis-using-the-canadian-multicentre-osteoporosis-study/