The Sub-Saharan Stroke Score (S4)
A simple bedside tool built from African stroke data, to help clinicians tell ischemic from hemorrhagic stroke when brain imaging isn’t available.
Why We Needed a New Score
The first big decision in stroke care is whether the stroke is ischemic (a blocked blood vessel) or hemorrhagic (a bleeding vessel). The treatments are very different, and clot-busting drugs that help one type can be fatal in the other.
A CT or MRI scan answers the question within minutes. In much of Sub-Saharan Africa, scanning can take hours or days, and many district and rural hospitals have no working scanner at all. Nurses and doctors must decide at the bedside.
Older bedside tools, like the Siriraj Stroke Score, were built on a small group of patients from a single hospital in Thailand, and they have performed unevenly in African populations. We set out to build a score from African data.
15
Imaging-Confirmed Studies
Hospital studies from Ethiopia, Nigeria, Tanzania, Zambia, Burkina Faso, Sierra Leone and South Africa
~3,000
Patients Analyzed
Adults whose stroke type was confirmed by brain imaging
5
Bedside Findings
Only five easy-to-check findings made the cut, with no lab tests or equipment needed
The S4 Score at a Glance
Each finding is worth points toward one stroke type or the other. Tap the findings below to see how they add up.
S4 = 7.29 × altered consciousness + 6.96 × vomiting + 2.43 × hypertension − 3.95 × hemiparesis/hemiplegia − 5.25 × diabetes
Total S4 score
0.00
Select the findings a patient presents with.
How to read it: a finding counts as 1 if present and 0 if absent. A total above 0 suggests a hemorrhagic stroke; 0 or below suggests an ischemic stroke. This is an educational illustration of the published formula, not a clinical tool.
The Evidence Behind Each Finding
We tested 15 possible findings across the pooled African studies. These five were the only ones that differed significantly between stroke types.
| Finding | Ischemic patients | Hemorrhagic patients | More common in | p-value |
|---|---|---|---|---|
| Altered consciousness | 27.2% | 43.6% | Hemorrhagic | < 0.0000001 |
| Vomiting | 9.4% | 17.2% | Hemorrhagic | 0.0002 |
| Hypertension | 53.7% | 59.6% | Hemorrhagic | 0.014 |
| Hemiparesis / hemiplegia | 73.0% | 64.6% | Ischemic | 0.0002 |
| Diabetes mellitus | 11.7% | 7.3% | Ischemic | 0.001 |
Percentages are pooled across the included studies. Findings that did not reach significance, including headache, past stroke, atrial fibrillation, HIV and smoking, were left out of the score.
Why S4 Matters
When a scanner is hours or days away, a structured, evidence-based starting point can make early decisions faster and more consistent.
Built for Africa
Designed from African patient data rather than adapted from cohorts elsewhere, reflecting local risk factors and disease patterns.
Simple and interpretable
Five yes/no findings and one sum. Frontline nurses and clinicians can see exactly why the score points one way or the other.
No equipment required
Every input can be gathered at the bedside in minutes, which suits district and rural facilities with limited resources.
Where S4 Could Help
Potential use-cases, once the score has been validated in clinical settings.
Early triage
Help nurses and physicians prioritize interventions and decide how closely to monitor a patient while awaiting imaging.
Referral and transfer decisions
Support the call on whether a patient should be sent on to a facility with a scanner, and how urgently.
Training and awareness
Give health workers a clear framework for which bedside signs matter most, complementing our posters and community education.
Mobile decision support
Because S4 is a short formula, it can be built into simple mobile tools and clinical workflows for low-resource settings.
Help Us Improve S4
Are you a clinician, hospital, or researcher in Sub-Saharan Africa interested in implementing S4 in your setting? We would love to hear from you.
Contact Us