Public Has Concerning Response to Learning Adverse Drug Event Information

Evaluating adverse events of medications plays a vital role in post-marketing surveillance of clinical research—but how effective are these results when it comes to influencing public response? A recent University of Queensland School of Pharmacy study, published in BMC Health Services Research, that investigated medication usage following exposure of their adverse events suggests that there are still necessary improvements to be made in information dispersal before consumers can be safely and accurately influenced.

The Australian study investigated changes in usage patterns of the COX-2 inhibitor rofecoxib and anti-osteoporosis bisphosphonates after 2 events: the removal of rofecoxib from market after the discovered risk of myocardial infarction (MI) in 2004 and the publicity surrounding the risk of jaw necrosis with bisphosphonates in 2007.

Quantified medication usage data was obtained from the Pharmaceutical Benefits Scheme (PBS) and national Australian population was obtained from the Australian Bureau of Statistics and Centrelink.

According to the COX-2 inhibitors data, celecoxib and rofecoxib were the market leaders before rofecoxib was withdrawn from market—after which celecoxib dispensing spiked, and then declined for several months. Around the same time, however, meloxicam (another COX-2 inhibitor) usage increased until it reached celecoxib usage levels. Lumiracoxib, a COX-2 inhibitor that was introduced to market in 2006 but withdrawn by 2007, also reached similar levels in the short time period before withdrawal—and at a faster rate. After lumiracoxib withdrawal, celecoxib and meloxicam usage levels did not decrease significantly.

Anti-osteoporosis bisphosphonate data showed that bisphosphonate usage peaked in 2007, when warnings about jaw osteonecrosis began being published in Australia. After 2007, alendronate usage declined, but risedronate and zoledronic acid usage increased.

The results of the study indicate an overall concerning public response to learning of adverse effects of a drug class.

As seen in the decrease in usage of rofecoxib after its market withdrawal, consumers understand the importance of stopping medication that they hear specific adverse effects for. However, the simultaneous increase in usage of other COX-2 inhibitors around the same time indicates that they simply switched to other medications in the same class instead. The risk of MI did not seem to occur to people as being a class effect. The lack of response in COX-2 inhibitor use after lumiracoxib withdrawal (a second withdrawal from the same drug class in a 2-year time period) is also concerning.

As seen in the decrease of alendronate usage after negative warnings of jaw osteonecrosis first began hitting Australia, consumers seem to be strongly affected by what they see in the media. Even though jaw osteonecrosis is a serious adverse effect of bisphosphonates, the risk is relatively rare. Marketing expenditure was increased substantially for risedronate following publicity about osteonecrosis and now risedronate is now the market leader over alendronate.

Results of this study have led the authors to call for tracking of medication classes after adverse events have been reported for 1 member of the class, and prospective collection and monitoring of information; and in terms of pharmaceutical publicity—real-time analysis of content with unbiased information for prescribers and consumers.

“Concepts of risk and benefit need to be clearly defined and made transparent for consumers,” the authors wrote. “New methods for post-market surveillance including updating of risks and benefits from new medications which evolve from utilization in large numbers of ‘real life’ people need to be incorporated in a systematic and unbiased information resource.”