醫學新聞 － Clinical Decision Rules to Identify Patients at High Risk for Subarachnoid Hemorrhage 蜘蛛膜下腔出血的臨床決策…

話說某年某月某日，某個中年女性頭痛來到急診，抽血打止痛針完，醫生說回家休息門診追蹤就好，結果病人才走到急診門口，突然砰一聲倒地不起沒有呼吸心跳，急救回來之後做了電腦斷層，結果是蜘蛛膜下腔出血…(以上為模擬真實案例)

頭痛是急診室不少見的問題，到底怎樣的人需要近一步檢查？怎樣的人給藥症狀治療就好。尤其面對病人要你保證＂沒有問題＂時候必須選擇的防衛性醫療；和背後健保局為了節省醫療支出所祭出的事後審查－砍你沒有發現到異常的昂貴檢查(好比電腦斷層)－以及醫院扣你薪水，這樣的兩面夾擊之下，急診室醫師常常陷入兩難煎熬…

Clinical Decision Rules to Identify Patients at High Risk for Subarachnoid Hemorrhage - General Medicine Journal Watch
這是來自加拿大的研究，花了五年的時間蒐集了將近兩千個突然頭痛起來或是頭痛又有昏倒掛急診、而神經學檢查又都正常的病患(突然的定義是說頭痛程度在一個小時內達到最痛)，為了找出怎樣的病人是蜘蛛膜下腔出血的高危險群。而最終結果是在1999個病人中有130個病人是蜘蛛膜下腔出血。
在病人蒐集方面，是希望儘量單純化(排除轉診或是已經有神經學異常的病患)、新發作的頭痛患者(排除反覆慢性頭痛)。

注意：蜘蛛膜下腔出血也有可能神經學檢查正常

Study population

We included alert patients aged ≥16 who presented to an emergency department with a chief complaint of non-traumatic headache peaking within an hour or of syncope associated with a headache. Alert was defined as a score of 15 on the Glasgow coma scale. Non-traumatic was defined as the absence of falls or direct trauma to the head in the previous seven days. Acute was defined as an interval of less than one hour from headache onset to peak intensity, and an interval of less than 14 days from headache onset to presentation.

We excluded patients with a history of three or more recurrent headaches of the same character and intensity as the presenting headache over a period of over six months; referred from other centres with a confirmed subarachnoid haemorrhage by either computed tomography or lumbar puncture; returned for reassessment of the same headache if they had already been investigated with computed tomography or lumbar puncture, or both; with papilloedema (as determined by treating physician); new focal neurological deficits, previous diagnosis of cerebral aneurysm or subarachnoid haemorrhage; previous diagnosis of a brain neoplasm; or known hydrocephalus.

RESULTS 

其實可以看到，加拿大的急診醫師，對於這類族群的頭痛患者，做電腦斷層的比率是很高的！有80%病人接受了電腦斷層檢查…但是實際上只有6.5%是SAH。

根據統計結果，發展了三個clinical decision rule －臨床決策規則－目的是希望在這些神經學檢查正常的病患中(有異常的當然二話不說就切CT去了)，找出那些特徵是高危險群，再來接受近一步檢查，以減少電腦斷層的使用。

• Rule 1: age ≧40, complaint of neck pain or stiffness, witnessed loss of consciousness, onset of headache with exertion
• Rule 2: arrival by ambulance, age ≧45, vomiting at least once, diastolic blood pressure ≧100 mm Hg
• Rule 3: arrival by ambulance, systolic blood pressure ≧160 mm Hg, complaint of neck pain or stiffness, age 45–55

如果利用這三個臨床決策規則來協助診斷，都可以減少電腦斷層之類檢查的使用率，從原本的八成減少到七成~六成；同時敏感度(Sensitivity)和陰性預測值(Negative Predictive Value)也都可以達到百分之百－翻成白話就是＂號稱＂不會漏掉任何一個SAH的病人啦！(40歲以下的人就不會有神經學檢查正常的SAH??)

至於這個研究在我們台灣可以應用嗎？不想用EBM方式去分析，至少我覺得人種差異讓這樣的臨床規則是否一體適用，還要再斟酌；況且＂搭救護車來急診＂這個指標，就會在台灣有很大不同的結果…Journal Watch的編輯寫到：

Comment: Although these decision rules are promising, they must be validated in other populations before they are used routinely; indeed, the authors note that a prospective validation study is under way. But, in the meantime, the findings provide guidance: Patients who present with nontraumatic headaches that peak within 1 hour and who have any of the clinical characteristics mentioned in the rules above should be assessed carefully for SAH. As the authors note, validated rules "could allow clinicians to be more selective and accurate when investigating patients with headache" and lower use of CT and lumbar puncture.

最後是帶回家的點(？)

回到開頭；至於曾經經歷過類似一開始我描述情境的同學們(or學長學弟學姐學妹們)~~看看自己的經驗有沒有可以套用到這個規則！結論就私下跟我說吧~~

original article from BMJ
High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study -- Perry et al. 341 -- bmj.com

上面這篇的correction 改正＞(大於)為≧(大於等於)