Updated: November 25 2024

Update Authors: Dr. Adrian Lau, Dr. Rowena Ridout, Dr. Laetitia Michou, Dr. Claudia Gagnon, Dr. Vithika Sivabalasundaram, Dr. Emma Billington, Dr. Zahra Bardai

A study published by Drieling and colleagues 2017 (1) described the results of a cohort study of 5120 older women with an average age of 80 years and at high fracture risk. This observational study from the Women’s Health Initiative included 5120 women who had been using oral bisphosphonates for at least 2 years and had a 5-year hip fracture risk of 1.5% or higher. Women who had been on parathyroid analogues, calcitonin or aromatase inhibitors were excluded. The average follow-up data was available for 4 years.

10-13 years of oral bisphosphonate use was associated with a higher risk of any clinical fracture than 2 years of use (HR =1.29, 95% CI 1.07-1.57).

There was no association between intermediate use and fracture risk. There are a number of limitations to this observational data including the fact that this study did not include a group without bisphosphonate use.  Also, compliance was not evaluated.

Oral bisphosphonates have been shown to significantly reduce the risk of vertebral and nonvertebral fracture in randomized controlled trials. Among patients with osteoporosis (defined as T-score < -2.5, or prior fragility fracture), bisphosphonate therapy provides a risk reduction of about 50% for vertebral, 30% for hip, and 20% for nonvertebral fractures after 3 years of treatment. The extension studies of these fracture trials unfortunately were not powered to evaluate impact on fracture risk.  Currently we do not have data consistently demonstrating reductions in nonvertebral fracture risk with long-term bisphosphonate use.

It appears that the optimal period of use for oral or IV bisphosphonates is 3-6 yrs with published randomized controlled trial data confirming reductions in fracture risk for vertebral, nonvertebral and hip fracture with use for this time period.

Osteoporosis Canada advises that all patients should have their fracture risk and treatment strategy reviewed by their physicians after 3-6 years of bisphosphonate use, as long-term use may not have the same risk-benefit ratio as seen with shorter term use.

1. Drieling RL, LaCroix AZ, Beresford SAA, Boudreau DM, Kooperberg C, Chlebowski RT, Ko MG, Heckbert SR. Long-Term Oral Bisphosphonate Therapy and Fractures in Older Women: The Women’s Health Initiative. J Am Geriatr Soc. 2017 Sep;65(9):1924-1931. doi: 10.1111/jgs.14911. Epub 2017 May 29. PMID: 28555811; PMCID: PMC5603349.