The safety of all centrally registered drugs is closely monitored by the European Medicines Agency (EMA) through a new committee, the Pharmacovigilance Risk Assessment Committee (PRAC), which was launched in October 2012. The procedures include regular submission of periodic safety update reports (PSURs).
In November 2012, the PSUR for strontium ranelate, which encompassed a number of new randomized clinical trials, included an updated assessment of the overall safety of the treatment and was submitted to the PRAC. The overall safety analyses showed an increased cardiovascular risk in patients treated with strontium ranelate. This ongoing process has led to a label change, and, in order to mitigate the cardiovascular risk, strontium ranelate is now contraindicated in patients with a history of cardiovascular disease, i.e. in patients with a history of ischemic heart disease, peripheral artery disease, and/or cerebrovascular disease and in those with uncontrolled hypertension.
In the light of these procedures, the results of two new studies were published together online on December 10, 2013, in Osteoporosis International. Both constitute retrospective observational studies conducted in databases of electronic healthcare records and were set up to analyze the cardiovascular risk associated with the prescription of strontium ranelate in
real-life clinical practice in the UK and in Denmark.
The results of the studies are consistent on three points. First, observational data do
NOT indicate that the use of strontium ranelate was associated with a significant increase in myocardial infarction (MI). Cooper et al. compared the risk of ischemic cardiac events in postmenopausal osteoporotic women who were currently receiving treatment with strontium ranelate—or had received it in the past—with the risk in those who had never received strontium ranelate. Current use or past use of strontium ranelate was not associated with any significant increase in the risk for three cardiovascular events: first MI, hospitalization with MI, or cardiovascular death. Abrahamsen et al. reported that the risk for MI in men and postmenopausal women was not significantly elevated, though they did find a very borderline result for stroke and cardiovascular death and a significant increase in risk for all-cause mortality.
Second, both studies highlighted substantial differences in patient profile of users of strontium ranelate compared with users of other osteoporosis treatments. Strontium ranelate patients are generally older and have more severe osteoporosis and a longer duration of disease. They also have more comorbidities, notably those related to elevated cardiovascular risk, such as cardiac failure (22 % in the Danish study), peripheral vascular disease (6 %), and cerebrovascular disease (11 %), with a combined prevalence of ischemic heart disease, peripheral vascular disease, and cerebrovascular disease of 19 % in women and 30 % in men. The cases of ischemic cardiac events in the UK study were also at substantially higher risk compared with the controls, with higher rates of history of hospitalization for MI (12 versus 4 %), ischemic heart disease (71 versus 24 %), peripheral artery disease (18 versus 7 %), and cerebrovascular disease (23 versus 15 %).
This is a significant finding for clinical practice: the majority of cases of MI occurred in patients who would not be treated with the agent according to the new contraindications for strontium ranelate.
Third, while both studies are highly robust, neither managed to properly address the major challenge of the potential channeling bias by which more fragile or severe patients are being switched to strontium ranelate. Clearly, further research is warranted with appropriate handling of the remaining bias for a more complete evaluation of risk.
The role of the clinician is to select the best treatment for the patient’s profile and individual therapeutic objective, which should remain the prevention of osteoporotic fracture. By strictly applying the new contraindications for strontium ranelate, we can hope to achieve our primary goal of treating disease, preventing osteoporotic fracture, while markedly reducing the risk for side effects.
http://link.springer.com/article/10.1007/s00198-013-2583-3/fulltext.html