'Nonserious' side effects may lead to antiplatelet discontinuation

By Eleanor McDermid

Most adverse events that lead patients to discontinue antiplatelet drugs are not rated as serious by clinical trial criteria, shows analysis of the PEGASUS-TIMI 54 trial.

Most patients who discontinued ticagrelor during the trial did so because of dyspnoea or bleeding, report Marc Bonaca (Brigham and Women's Hospital Heart and Vascular Center, Boston, Massachusetts, USA) and colleagues.

However, dyspnoea was generally rated as mild or moderate by the study investigators and bleeding as nonmajor.

In all, 6.5% of the 6988 patients taking ticagrelor 90 mg twice daily discontinued because of dyspnoea, as did 4.6% of the 6958 taking the 60 mg twice-daily dose. But only 2% and 4%, respectively, of these discontinuations were due to a serious adverse event, and just 13% and 8% of dyspnoea events leading to discontinuation were severe. More than half were rated moderate, and nearly a third were mild.

The rates of discontinuation for bleeding were 7.8% and 6.2% in the 90 mg and 60 mg ticagrelor groups, respectively, and of these 13% and 15% were given a TIMI classification of major bleeding. But all other events were regarded as nonmajor, with 21% and 19% rated as minimal (not requiring medical attention or resulting in a haemoglobin reduction).

Patients most commonly discontinued medication during the first year of treatment, at rates of up to 24.1%, with most discontinuations occurring within the first 90 days.

"Among patients who completed 1 year of treatment, the subsequent rates of discontinuation were low", writes the team in JAMA Cardiology. Only around 7% of patients discontinued after this point.

Writing in an accompanying commentary, Christopher Granger (Duke University, Durham, North Carolina, USA) and Peter Berger (Northwell Health, New York, USA) point out that persistence with preventive medications is considerably worse in registry-based studies of unselected patients than in clinical trials.

"Thus, the development of systems to improve persistent use of secondary prevention therapies ought to be a high priority", they say.

"Patient education and engagement with behavioral tools will be important when attempting to maximize adherence, especially to treatments that do not make patients feel better while they are receiving them, such as antiplatelet therapy."

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