Assessing short-term risk of ischemic stroke in relation to all prescribed medications.

We examined the short-term risk of stroke associated with drugs prescribed in Norway or Sweden in a comprehensive, hypothesis-free manner using comprehensive nation-wide data. We identified 27,680 and 92,561 cases with a first ischemic stroke via the patient- and the cause-of-death registers in Norway (2004-2014) and Sweden (2005-2014), respectively, and linked these data to prescription databases. A case-crossover design was used that compares the drugs dispensed within 1 to 14 days before the date of ischemic stroke occurrence with those dispensed 29 to 42 days before the index event. A Bolasso approach, a version of the Lasso regression algorithm, was used to select drugs that acutely either increase or decrease the apparent risk of ischemic stroke. Application of the Bolasso regression algorithm selected 19 drugs which were associated with increased risk for ischemic stroke and 11 drugs with decreased risk in both countries. Morphine in combination with antispasmodics was associated with a particularly high risk of stroke (odds ratio 7.09, 95% confidence intervals 4.81-10.47). Several potentially intriguing associations, both within and across pharmacological classes, merit further investigation in focused, follow-up studies.

Stroke risk after transient ischemic attack in a Norwegian prospective cohort.

BACKGROUND: Transient ischemic attack (TIA) is a risk factor of stroke. Modern treatment regimens and changing risk factors in the population justify new estimates of stroke risk after TIA, and evaluation of the recommended ABCD2 stroke risk score. METHODS: From October, 2012, to July, 2014, we performed a prospective, multicenter study in Central Norway, enrolling patients with a TIA within the previous 2 weeks. Our aim was to assess stroke risk at 1 week, 3 months and 1 year after TIA, and to determine the predictive value of the dichotomized ABCD2 score (0-3 vs 4-7) at each time point. We used data obtained by telephone follow-up and registry data from the Norwegian Stroke Register. RESULTS: Five hundred and seventy-seven patients with TIA were enrolled of which 85% were examined by a stroke specialist within 24 h after symptom onset. The cumulative incidence of stroke within 1 week, 3 months and 1 year of TIA was 0.9% (95% CI, 0.37-2.0), 3.3% (95% CI, 2.1-5.1) and 5.4% (95% CI, 3.9-7.6), respectively. The accuracy of the ABCD2 score provided by c-statistics at 7 days, 3 months and 1 year was 0.62 (95% CI, 0.39-0.85), 0.62 (95% CI, 0.51-0.74) and 0.64 (95% CI, 0.54-0.75), respectively. CONCLUSIONS: We found a lower stroke risk after TIA than reported in earlier studies. The ABCD2 score did not reliably discriminate between low and high risk patients, suggesting that it may be less useful in populations with a low risk of stroke after TIA. TRIAL REGISTRATION: Unique identifier: NCT02038725 (retrospectively registered, January 16, 2014).