Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death: a cohort study.

BACKGROUND: We wished to examine the impact of antiplatelet drug discontinuation on recurrent stroke and all-cause mortality.
METHODS: We identified a cohort of incident ischaemic stroke patients in a Danish stroke registry, 2007-2011. Using population-based registries we assessed subjects' drug use and followed them up for stroke recurrence, or all-cause death. Person-time was classified by antiplatelet drug use into current use, recent use (≤150 days after last use), and non-use (>150 days after last use). Lipid-lowering drug (LLD) use was classified by the same rules. We used Cox proportional hazard models to calculate the adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) for the risk of recurrent stroke or death associated with discontinuation of antiplatelet or LLD drugs.
RESULTS: Among 4,670 stroke patients followed up for up a median of 1.5 years, 237 experienced a second stroke and 600 died. Compared with current antiplatelet drug use, both recent use (1.3 (0.8-2.0)), and non-use (1.3 (0.8-1.9)) were associated with increased recurrent stroke risk. The corresponding HRs of death were 1.9 (1.4-2.5) for recent and 1.8 (1.4-2.3) for non-use of antiplatelet drugs. Recent statin use was associated with markedly increased risk of death (2.1 (1.7-2.6)), and only marginally with recurrent stroke (1.2 (0.9-1.6)).
CONCLUSIONS: Antiplatelet drug discontinuation may be associated with an increased recurrent stroke risk. Our results on death risk indicate that non-pharmacological biases, such as 'sick stopper', may threaten the validity of this risk estimate.