Systolic blood pressure as a predictor of transient ischemic attack/minor stroke in emergency department patients under age 80: a prospective cohort study

Abstract

Background: Elevated blood pressure (BP) at emergency department (ED) presentation and advancing age have been associated with risk of ischemic stroke; however, the relationship between BP, age, and transient ischemic attack/minor stroke (TIA/MS) is not clear.

Methods: A multi-site, prospective, observational study of 1084 ED patients screened for suspected TIA/MS (symptom onset < 24 h, NIHSS< 4) between December 2013 and April 2016. Systolic and diastolic BP measurements (SBP, DBP) were taken at ED presentation. Final diagnosis was consensus adjudication by stroke neurologists; patients were diagnosed as either TIA/MS or stroke-mimic (non-cerebrovascular conditions). Conditional inference trees were used to define age cut-points for predicting binary diagnosis (TIA/MS or stroke-mimic). Logistic regression models were used to estimate the effect of BP, age, sex, and the age-BP interaction on predicting TIA/MS diagnosis.

Results: Over a 28-month period, 768 (71%) patients were diagnosed with TIA/MS: these patients were older (mean 71.6 years) and more likely to be male (58%) than stroke-mimics (61.4 years, 41%; each p < 0.001). TIA/MS patients had higher SBP than stroke-mimics (p < 0.001). DBP did not differ between the two groups (p = 0.191). SBP was predictive of TIA/MS diagnosis in younger patients, after accounting for age and sex; an increase of 10 mmHg systolic increased the odds of TIA/MS 18% (odds ratio [OR] 1.18, 95% CI 1.00-1.39) in patients < 60 years, and 23% (OR 1.23, 95% CI 11.12-1.35) in those 60-79 years, while not affecting the odds of TIA/MS in patients ≥80 years (OR 0.99, 95% CI 0.89-1.07).

Conclusions: Raised SBP in patients younger than 80 with suspected TIA/MS may be a useful clinical indicator upon initial presentation to help increase clinicians' suspicion of TIA/MS.

Trial registration: ClinicalTrials.gov NCT03050099 (10-Feb-2017) and NCT03070067 (3-Mar-2017). Retrospectively registered.

Keywords: Blood pressure; Emergency medicine; Minor stroke; TIA; Transient ischemic attack.

Fig. 1

Relationship between systolic blood pressure and (a) final diagnosis, b TOAST classification, and between diastolic blood pressure and (c) final diagnosis, d TOAST classification. Blood pressure sample means ± standard errors are plotted

Fig. 2

Conditional inference tree estimating the effects of age, sex, systolic blood pressure, diabetes, hypertension, and feelings of anxiety

Fig. 3

Nomogram for the reduced logistic regression model predicting TIA/minor stroke versus stroke-mimic with from sex and the interaction of age and systolic blood pressure. To use the nomogram for a patient with given SBP, age, and sex, use the ‘Points’ scale at the top of the figure to ascertain points for each variable aligning the scale vertically with the variable value. For example, for a male patient aged 50 with SBP of 120 mmHg, score 15 points for male and 15 points for age < 60 years with SBP of 120 mmHg. The ‘Total Points’ value is 30. Align the value of 30 on the ‘Total Points’ scale with the ‘Probability’ scale, to determine an approximate probability of TIA/MS of 0.40 for this patient. Note that the SBP points for patients older than 80 years decrease with increasing SBP as the SBP odds ratio for that group is less than one