Osteoporosis medication prescribing in British Columbia and Ontario: impact of public drug coverage

Abstract

SummaryWe compared the patterns of osteoporosis medication prescribing between two provinces in Canada with different public drug coverage policies. Oral bisphosphonates were the primary drugs used, yet access to the second-generation oral bisphosphonates (alendronate, risedronate) was limited in one region. Implications of differential access to oral bisphosphonates warrants further study.IntroductionApproved therapies for treating osteoporosis in Canada include bisphosphonates, calcitonin, denosumab, raloxifene, and teriparatide. However, significant variation in access to these medications through public drug coverage exists across Canada. We sought to compare patterns of osteoporosis medication prescribing between British Columbia (BC) and Ontario.MethodsUsing dispensing data from BC (PharmaNet) and Ontario (Ontario Drug Benefits), we identified all new users of osteoporosis medications aged 66 or more years from 1995/1996 to 2008/2009. We summarized the number of new users by fiscal year, sex, and index drug for each province. BC data were also stratified by whether drugs were dispensed within or outside public PharmaCare.ResultsWe identified 578,254 (n = 122,653 BC) eligible new users. Overall patterns were similar between provinces: (1) most patients received an oral bisphosphonate (93% in BC and 99% in Ontario); (2) etidronate prescribing declined after 2001/2002, reaching a low of 41% in BC and 10% in Ontario in 2008/2009; and (3) the proportion of males treated increased over time, from 7% in 1996/1997 to 25% in 2008/2009. However, we note major differences within versus outside the BC PharmaCare system. In particular, <2% of drugs dispensed within PharmaCare compared to 79% of drugs dispensed outside PharmaCare were for a second-generation bisphosphonate (alendronate or risedronate).ConclusionsOral bisphosphonates are the primary drugs used to treat osteoporosis in Canada. Prescribing practices changed over time as newer medications came to market, yet access to second-generation bisphosphonates through BC PharmaCare was limited. Implications of differential access to oral bisphosphonates warrants further study.

An Introduction to Health Care Administrative Data

“…As an example, when our team used drug dispensing data to compare incident drug prescribing between provinces, we found significant differences between drug plans. 11 The definition of incident (new), prevalent (current), or past (history) drug use is typically based on a minimum length of time (e.g., a 1-year period) before the first date of drug dispensing that defines study entry. 12 Drug dispensing data can also be used to examine the effect of new drug coverage policies on physicians' prescribing practices and characterize prescribers (e.g., by age, sex, specialty, and practice region) as well as patients (e.g., by age, sex, drug and health history, and other factors).…”

“…Entry of new drugs to the market and changes to reimbursement criteria or coverage can significantly affect drug utilization and patient characteristics. 11,13 As described in the primer on cohort and case-control studies, 27 "confounding by indication" is natural in any study that examines the effects of pharmacotherapy, since drugs are always prescribed (indicated) to mitigate risk, i.e., to prevent or treat a condition and thus reduce the risk of harm. Confounding is not a problem in the context of complete information, since researchers can use statistical methods to adjust for differences between exposure groups under comparison.…”

Patterns of use for brand-name versus generic oral bisphosphonate drugs in Ontario over a 13-year period: a descriptive study

“…4 In Canada, alendronate and risedronate are prescribed most often. 5 Both medications have proven efficacy in fracture prevention and are generally welltolerated. [6][7][8][9] In the province of Ontario, the Ontario Drug Benefit (ODB) Program funds prescription medication for patients aged 65 years and older.…”

Study design considerations for a large simple trial of bisphosphonates

“…Oral bisphosphonates are the most widely used osteoporosis agents [1,2]; therefore, it may be clinically relevant to evaluate fracture risk reduction in an initiation (head-tohead randomization of two oral agents) or discontinuation LST (current use of one or more oral agents, randomized to either continue or stop therapy). Alternatively, there are several other classes of agents used in the treatment of osteoporosis, including selective oestrogen receptor modulators, parathyroid hormone and receptor activator of nuclear factor kappa-B (RANK) ligand inhibitors.…”

“…A few head-to-head randomized controlled trials (RCTs) of bisphosphonates, the most commonly used osteoporosis agent [1,2], have examined surrogate outcomes, such as bone mineral density [3][4][5][6], but not fractures, the ultimate outcome of interest in osteoporosis. A few head-to-head randomized controlled trials (RCTs) of bisphosphonates, the most commonly used osteoporosis agent [1,2], have examined surrogate outcomes, such as bone mineral density [3][4][5][6], but not fractures, the ultimate outcome of interest in osteoporosis.…”