March 22, 2010 — 包含「嚴重高血壓(severe hypertension[S])、意識混亂(confusion[C])、抗凝血劑(anticoagulation[A])以及噁心嘔吐(nausea and vomiting[N])；簡稱SCAN規則」等四項症狀的規則，在輕微中風病患的顱內出血(intracerebral hemorrhage[ICH])辨識上似乎具有特定性與敏感度。
Lovelock醫師、Kerr醫師以及Al-Shahi Salman醫師皆宣告沒有相關財務關係，該研究使用的資料來自「Oxford Vascular Study」這項由英國醫學研究委員會、Dunhill醫學信託基金、中風協會、BUPA基金會、國家健康研究中心(NIHR)、Thames Valley Primary Care Research Partnership以及NIHR牛津生醫研究中心等資助的研究。
SCAN Rule May Reduce Misdiagnosis of ICH in Patients With Minor Stroke
By Emma Hitt, PhD
Medscape Medical News
March 22, 2010 — A rule involving 4 symptoms — severe hypertension (S), confusion (C), anticoagulation (A), and nausea and vomiting (N) — appears to be specific and sensitive at identifying intracerebral hemorrhage (ICH) in patients with minor stroke.
The SCAN rule states that if at least 1 of these 4 predictive variables is present in a patient with minor stroke, the patient is likely to have ICH. The rule may help determine which patients can be safely treated immediately with antiplatelet agents compared with those who might have ICH and would need further brain imaging (magnetic resonance imaging [MRI] or computed tomography [CT]) before treatment.
Caroline E. Lovelock, MBChB, DPhil, FRACP, formerly with the John Radcliffe Hospital in Oxford, United Kingdom, and now with the Department of Neurology at St. George's Hospital Medical School in London, United Kingdom, and colleagues published their findings in the March issue of Journal of Neurology, Neurosurgery Psychiatry.
"Because CT brain imaging becomes insensitive to an acute bleed after only a few days, the SCAN rule is particularly useful for identifying which late-presenting patients need priority access to MRI brain imaging so that the risk of misdiagnosing an ICH can be minimized," Dr. Lovelock told Medscape Neurology.
The researchers sought to identify clinical factors associated with ICH in 334 consecutive patients with minor stroke, defined as a National Institutes of Health Stroke Scale score of 3 or less. The predictive model derived in this cohort was then further validated in a separate cohort of 280 patients. Approximately 5% of patients in the initial and validation cohorts had ICH.
"In the hospital clinic validation cohort, at least 1 clinical predictor was present in 24% of patients but in 93% of patients with ICH," the study authors write. "If 2 or more clinical predictors were present, 25% of patients had evidence of ICH on scan."
Data pooled from the derivation and validation cohorts indicated that the SCAN rule had a sensitivity of 97% (95% confidence interval [CI], 84% – 99%) and a specificity of 74% (95% CI, 70% – 77%) for the detection of ICH.
Utility in Various Healthcare Settings
The SCAN rule, which is applicable to late-presenting patients with minor stroke, should be useful in both the US and UK healthcare systems, Dr. Lovelock said. Even in a highly resourced healthcare system, she noted, "patients with minor stroke may still present late to medical attention, particularly if they are relatively socially or geographically isolated."
According to Dr. Lovelock, the SCAN rule may also be useful in poorer countries, "where it can be used to identify which patients with minor stroke need priority access to early CT imaging to rule out ICH," although it still requires validation in different healthcare settings.
Dr. Lovelock noted, though, that the SCAN rule should not be used as an alternative to brain imaging to diagnose ICH. "Instead it is a guide to help plan appropriate investigations and treatment for patients with minor stroke, in whom the possibility of an underlying ICH always needs to be considered."
Not an Alternative to Brain Imaging
According to a related editorial by Enda Kerr and Rustam Al-Shahi Salman with the University of Edinburgh, United Kingdom, "the most useful attribute of the SCAN rule might be its negative predictive value of 99.8% (95% CI, 99% – 100%).
"For the 70% of patients with minor stroke who had a SCAN score of zero, ICH was almost completely ruled out," they point out.
Still, although the SCAN rule almost "rules out ICH in patients with minor strokes and a SCAN score of zero, it is insufficient to completely refute the need for timely and appropriate brain imaging."
Brain imaging can also do more than exclude hemorrhage by identifying the vascular territory of an ischemic stroke, ruling out stroke "mimics" and potentially influencing prognosis estimates or management strategies, they add. "So, where brain imaging facilities permit, immediate brain scanning for all strokes remains the policy that is most cost-effective and results in the greatest gain in quality-adjusted life-years."
Dr. Lovelock, Dr. Kerr, and Dr. Al-Shahi Salman have disclosed no relevant financial relationships. The study used data from the Oxford Vascular Study, which is funded by the UK Medical Research Council, the Dunhill Medical Trust, the Stroke Association, the BUPA Foundation, the National Institute for Health Research (NIHR), the Thames Valley Primary Care Research Partnership, and the NIHR Oxford Biomedical Research Centre.
