Bisphosphonate and denosumab initiation in older adults in Ontario, Canada: a population-based cohort study

We provide an update on how commonly prescribed osteoporosis therapies are being initiated in older adults in Ontario. Patients newly prescribed denosumab are older, more often female, and have more comorbidities than those prescribed bisphosphonates. Their characteristics, monitoring, and persistence with prescribed therapy differ from clinical trial participants. Real-world studies on oral bisphosphonates and denosumab might be valuable.

To provide a contemporary view on oral bisphosphonate and denosumab prescribing to older adults in routine care.

Using linked healthcare databases, we conducted a population-based cohort study of adults ≥ 66 years newly prescribed oral bisphosphonates or denosumab between February 2013 and March 2017 in Ontario, Canada. We captured their clinical characteristics, monitoring, and continuous use of prescribed therapies. We illustrate how "real-world" new users of bisphosphonates and denosumab differ from randomized controlled trial (RCT) participants.

There were 107,847 individuals newly prescribed oral bisphosphonates (n = 59,996) or denosumab (n = 47,851) over the study period. Compared with new users of oral bisphosphonates, denosumab users were older (mean age 79.1 vs. 75.7 years), more often female (97.2 vs. 71.8%), from non-rural areas (93.9 vs. 89.9%), and resided in long-term care (10.9 vs. 3.3%). They had more comorbidities including dementia, falls, and fractures. Following their new prescription, denosumab users had more frequent testing of serum calcium. Duration of continuous use of denosumab was longer than bisphosphonates, and more bisphosphonate users had evidence of treatment discontinuation (56.7 bisphosphonate vs. 33.8% denosumab users discontinued therapy at 365 days). Compared with RCT participants, a higher proportion of "real-world" bisphosphonate and denosumab users had comorbidities including advanced kidney disease.

The clinical characteristics and monitoring of new users of bisphosphonates and denosumab generally align with practice guidelines, product monographs, and drug reimbursement criteria. Given differences between real-world users and RCT participants, there may be a role for safety and effectiveness studies of bisphosphonates and denosumab in routine care.