Knowledge gap in a cross section of Irish general practitioners prescribing denosumab for osteoporosis

To our knowledge, this is the only study in Ireland that has explored both GP knowledge and clinical practice with regard to denosumab in the treatment of osteoporosis. We identified a knowledge gap in a number of areas, especially with regard to stopping treatment and follow-up therapy.

While the majority of GPs had used denosumab in the preceding year, close to half had prescribed it as first a first line treatment. In a recent study of 1146 Irish patients prescribed denosumab by GPs between 2012 and 2017, over half had no prior bone therapy suggesting a rate of first line use not explained by contraindications to other therapies [2]. We found that in a third of the cases, ‘convenience’ was cited as an indication for first line use; however, no other Irish studies have explored the reasons for denosumab prescribing. Other studies elsewhere have shown that patients have a preference for a six monthly injection compared to weekly tablets, with convenience being identified as an important factor [8]. This is likely to impact on GPs who take patient preferences into consideration when prescribing osteoporosis medications [9].

About half of GPs envisaged therapy duration for 3–5 years with practice nurses administering the injection in most cases. However, it is unclear how this compares to practice elsewhere or whether the availability of nurses to administer injections could influence GPs prescribing of denosumab. A minority did not check serum calcium prior to the injection though while assessing serum calcium is recommended before drug administration it is not mandatory. Indeed, during COVID-19, some guidelines waivered the advice to check serum calcium in all patients if normal in the previous year due to difficulties with accessing bloods and advised clinical judgement on an individudal basis [10]. On the other hand, about one in six checked calcium routinely post injection which is not necessary. Indeed, at the end of denosumab therapy (i.e. at about 6 months or more after the last injection), there may also be a mild hypercalcaemia associated with rebound phenomenon [11] that could inadvertently lead to delay in the next injection. However, importantly, the majority of GPs did check serum calcium post injection in patients at risk of hypocalcaemia. Just over half of GPs cited a daily calcium intake of 1000 mg or more for patients with osteoporosis. By comparison, in a survey of GP knowledge of osteoporosis in the Czech Republic in 2017, 41% were reported to correctly state the recommended calcium intake [12].

Most GPs had no alert systems to remind patients of their next dose and about half cited relying on pharmacists. While persistence with denosumab in Irish patients has been found to be 57% at 2 years, it has been reported to be higher in those with a medical card [2]. Medical card holders in Ireland are entitled to medications at no cost, with reimbursement of their dispensing pharmacist by the Irish Department of Health. Pharmacy oversight of these prescriptions might contribute to this better persistence though avoidance of an ‘out of pocket’ expense is also likely to be an important factor.

A third were not aware of the need for timely denosumab administration (no longer than 7 months after the last injection) suggesting a lack of knowledge among some GPs of current guidelines. This was also more likely in GP registrars who might be less aware of recommendations. Perhaps not surprisingly, the majority of GPs felt there was a delay in denosumab injections during COVID-19 as has been reported elsewhere [13]. Interestingly, the paradigm of drug holiday was considered by 41% if stopping denosumab despite the vast majority having concerns if there was therapy cessation. However, a significant proportion were unclear as to what to do if stopping and might refer for specialist opinion. By comparison, in a recently published Australian study, GPs expressed uncertainty about when to stop denosumab, what to do when stopping, the risk of stopping without an alternative being prescribed, or what should be prescribed if a patient had previously had problems with bisphosphonates [9].

Consistent with the above, we found that the majority of GPs had no knowledge of recent guidelines on what do if denosumab is stopped with just over one-third citing the use of an antiresorptive therapy after cessation. A previous study in Ireland found that 6% of patients who stopped denosumab were started on alternative treatments by their GP [2] while in Australia, this was reported to be less than 20% [9]. However, both studies reported on GP practices at a time when knowledge of the phenomenon of rebound bone loss on denosumab cessation was only emerging [1]. GPs felt that the commonest reason for patients wanting to stop denosumab was concern about being on treatment too long which is a similar to what as been identifed for other osteoporosis drugs [14].

We acknowledge that only 17% of GPs contacted replied to our survey which could bias the findings. However, the response rate to Irish GP surveys has been identified to be similarily low in other studies with the same methodology [15,16,17,18]. The quality or representativeness of a survey also does not necessarily correlate with its size, and a lower response rate does not necessarily make a survey less accurate [19]. Furthermore, previous research suggests that GPs with less interest in a topic may be less likely to engage in surveys [20, 21]. Therefore, this survey could potentially underestimate the knowledge gap identified.

In conclusion, we identified a knowledge gap with regard to denosumab prescribing among a sample of Irish GPs, particularly with regard to cessation of therapy and follow-up treatments. Our findings suggest that there is a need for education to increase awareness around denosumab use. It also highlghts the need for reminder or recall systems in GP practices so as to avoid rebound fractures [9].

留言 (0)

沒有登入
gif