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Rapid high-volume population screening for three major risk factors of future stroke: phase I results
Philip S Mullenix1, Matthew J Martin, Scott R Steele
1Department of General Surgery, Madigan Army Medical Center, Tacoma, WA 98431-1100, USA.
Insights
A rapid screening protocol effectively identified significant prevalence of stroke risk factors like carotid stenosis, atrial fibrillation, and hypertension in health maintenance organization beneficiaries. This approach enables risk stratification for timely intervention and improved patient outcomes.
Area of Science:
- Neurology
- Cardiology
- Vascular Medicine
Background:
- Stroke is a leading cause of disability and death, with carotid stenosis, atrial fibrillation, and hypertension as key modifiable risk factors.
- Early identification and management of these risk factors are crucial for stroke prevention.
- A need exists for efficient screening protocols to identify at-risk populations within healthcare systems.
Purpose of the Study:
- To establish the prevalence of carotid stenosis, atrial fibrillation, and hypertension among health maintenance organization beneficiaries.
- To implement and evaluate a rapid screening protocol for stroke risk stratification.
- To stratify patients into risk cohorts for appropriate management and future outcome analysis.
Main Methods:
- Prospective study involving a rapid screening protocol including directed history, carotid 'quick-scan', EKG, and blood pressure measurements.
- Patients with abnormal screening results underwent specific diagnostic consultations and tests (e.g., carotid duplex ultrasound, 12-lead EKG, Holter monitor, 5-day BP check).
- Screening was conducted over 8 hours on a single day, involving 294 patients (mean age 69).
Main Results:
- Overall prevalence: carotid stenosis 6% (17/294), atrial fibrillation 7% (21/294), severe hypertension 5% (16/294).
- Rapid screening identified 20% positive for carotid stenosis, with 29% confirmed (>50% stenosis).
- Significant prevalence of previously undiagnosed conditions: 11% new arrhythmias, 54% moderate hypertension, 5% severe hypertension. 82% required further diagnostic tests.
- Risk stratification identified 11% as high risk, 64% as moderate risk, and 25% as low risk for future stroke.
Conclusions:
- A rapid and efficient screening protocol for stroke risk factors is feasible and effective in identifying a significant number of at-risk individuals.
- The prevalence of undiagnosed carotid stenosis, atrial fibrillation, and severe hypertension is substantial, highlighting the need for proactive screening.
- Phase II will investigate the impact of a multidisciplinary approach on stroke risk reduction through early identification and aggressive treatment.
Abstract:
Three proximate risk factors for stroke are carotid stenosis, atrial fibrillation, and hypertension. Phase I of this prospective study was designed to establish the prevalence of these conditions among a population of health maintenance organization beneficiaries by using a rapid screening protocol in order to risk-stratify patients for appropriate management and subsequent cohort analysis. Patients at a tertiary care medical center were screened for stroke risk by using directed history, a 3-minute carotid "quick-scan'' protocol, an EKG lead II rhythm strip, and bilateral arm blood pressures. Patients with any abnormal result underwent specific diagnostic consultation with vascular surgery, cardiology, or primary care. These evaluations included formal carotid duplex ultrasound, 12-lead EKG +/- Holter monitor, and 5-day blood pressure check. Patients were then stratified into risk cohorts for appropriate management and future analysis of stroke incidence and outcomes. In 8 hours on a single day in October 2002, 294 patients (mean age 69) were screened. Combining history with results of screening and diagnostic tests, the overall prevalence of carotid stenosis was 6% (n = 17/294), atrial fibrillation 7% (n = 21/294), and severe hypertension 5% (n = 16/294). Fifty-nine patients (20%) screened positive for carotid stenosis by "quick-scan,'' and 29% (n = 17/59) of these had confirmed stenosis (>50%) in 1 or both arteries by formal duplex. The prevalence of confirmed carotid stenosis was 37% among those screening positive for 1 artery (odds ratio [OR] 14.6; p<0.001) and 75% among those screening positive for both (OR 74.7; p<0.001). Significant independent predictors of carotid stenosis by multivariate analysis included coronary artery disease or myocardial infarction, smoking, stroke or transient ischemic attack, male gender, and white race (all p<0.05). The prevalence of confirmed stenosis was 10% with any 3 predictors alone (OR 2.5; p<0.05), 31% with any 4 (OR 21.2; p<0.001), and 50% with all 5 (OR 46.5; p<0.001). Thirty-three patients (11%) were found to have a previously unidentified and untreated arrhythmia, and 12% (n = 4/33) of these had confirmed new atrial fibrillation; 158 patients (54%) had moderate hypertension and 16 (5%) had severe hypertension (>180/100). Overall, 82% (n = 242/294) of patients screened required additional diagnostic tests. Based on these results, 11% (n = 31/294) of patients were stratified as high risk, 64% (n = 188/294) as moderate risk, and 25% (n = 75/294) as low risk for future stroke. Rapid and efficient screening of a large population for stroke risk factors is feasible. The prevalence of undiagnosed, unsurveilled, and untreated carotid stenosis, atrial fibrillation, and severe hypertension is significant, as 75% of patients screened had 1 or more confirmed major risk factors for stroke. Phase II of this study will investigate the degree of stroke risk reduction possible with a multidisciplinary approach to early identification and aggressive treatment of these risks.
