目前我(wo)國縣級以上包括縣醫院(yuan)均(jun)配(pei)置有(you)全自(zi)動生(sheng)化(hua)分(fen)析儀,甚至沿海縣區的(de)中心衛生(sheng)院(yuan)也配(pei)備了,絕大部(bu)分(fen)為自(zi)建檢測(ce)系統(tong)。問(wen)及校準他們會拿出來(lai)(lai)的(de)是K值(zhi)(zhi)記錄,問(wen)及K值(zhi)(zhi)怎(zen)么得來(lai)(lai)的(de)?都(dou)說用一個(ge)校準品的(de)標示值(zhi)(zhi)來(lai)(lai)定標,K值(zhi)(zhi)自(zi)動顯示。把(ba)一點定標作為校準對待,這(zhe)樣做對嗎?另(ling)一方(fang)面,使用校準品也有(you)問(wen)題(ti),這(zhe)些都(dou)值(zhi)(zhi)得深思。
一、校準與定標有無區別?
校(xiao)準與(yu)定標均來(lai)自(zi)英文“Calibrate”一(yi)詞,似乎沒有什么區別。讓(rang)我們首先(xian)復習一(yi)下(xia)校(xiao)準的定義(yi)和內涵。
我們查閱和溫習(xi)了《臨床實(shi)驗(yan)室質量控制(QC)》的(de)(de)要求,上面對(dui)“校準(zhun)”是(shi)這樣(yang)描述的(de)(de):“在一定(ding)條件下的(de)(de)一系(xi)列操作來確定(ding)檢測儀(yi)器和檢測系(xi)統(tong)所(suo)指示的(de)(de)量值(zhi)(zhi),或者(zhe)(zhe)某一物(wu)質,或者(zhe)(zhe)參考(kao)物(wu)質代(dai)表(biao)的(de)(de)值(zhi)(zhi),與相應標(biao)準(zhun)所(suo)認識(shi)量之間的(de)(de)關(guan)系(xi)。”接下來必(bi)需做“校準(zhun)驗(yan)證”,“就是(shi)要求按標(biao)本方式(shi)對(dui)校準(zhun)品(pin)進(jin)步分析,以檢查并證實(shi)儀(yi)器、試劑盒或檢驗(yan)系(xi)統(tong)的(de)(de)檢驗(yan)結果在規(gui)定(ding)的(de)(de)報告范圍內(nei)保持穩定(ding)。”這才是(shi)規(gui)范化的(de)(de)校準(zhun)過(guo)程(cheng)。
同時文件指出自己建立的檢測系統必須建立校準方法:
①選擇合適的(de)校(xiao)(標(biao))準品,包括校(xiao)(標(biao))準品的(de)數目、類型和濃度;
②如有可能,校(標)準品應溯源到參考(kao)方法和或參考(kao)物(wu)質(zhi);
③確定校準(zhun)的頻度(du)。
同時建立校準驗證方法:
①如有可能,方(fang)法應追溯到參考(kao)方(fang)法或己(ji)知值的參考(kao)品;
②確定(ding)校(xiao)(標)準(zhun)(zhun)品的(de)數(shu)目類型和濃度,校(xiao)準(zhun)(zhun)驗證的(de)接(jie)受限(xian),以(yi)及校(xiao)準(zhun)(zhun)驗證的(de)頻度;
③確定檢驗詰的報告范圍,確定時必須包括一個最小值,中間值和此范圍的上限的最大值。同時還規定六個月以及有下列情況發生時,進行一次校驗,如儀器或檢測系統進行過一次大的預防性維護或者更換了重要部件;質控反映出異常趨勢或偏移,或者超出了實驗室規定的接受限,采取一般性糾正措施后,不能識別和糾正問題時。最后特別強調所有進行過的校準和校準驗證工作時必須記錄并寫成文件。
馮仁豐教授在《CLIA’88更新規則介紹》報告中也論及校準和校準驗證(確認):“要求校準的項目,你必須繼續按照廠商要求,進行校準和校準確認(驗證)。但是,校準和校準確認(驗證)至少半年進行一次,在檢驗的可報告范圍內,至少用三個水平予以確認。”
通過上述(shu)文件和(he)專(zhuan)家報(bao)告(gao)學(xue)習,我們應該(gai)十(shi)分請楚校(xiao)(xiao)準(zhun)(zhun)(zhun)的(de)涵意,應該(gai)包括校(xiao)(xiao)準(zhun)(zhun)(zhun)和(he)校(xiao)(xiao)準(zhun)(zhun)(zhun)驗證兩個方面,正確的(de)校(xiao)(xiao)準(zhun)(zhun)(zhun)和(he)校(xiao)(xiao)準(zhun)(zhun)(zhun)驗證對于檢驗結果在規定(ding)的(de)報(bao)告(gao)范圍內(nei)的(de)準(zhun)(zhun)(zhun)確和(he)可(ke)靠(kao)是必要的(de)。
在(zai)正規文(wen)件中,我們還沒(mei)有找到“定標(biao)”的名(ming)詞(ci)解釋。但在(zai)儀器(qi)中文(wen)說明書上倒(dao)有定標(biao)名(ming)詞(ci)多次出(chu)現。二、“單(dan)點定(ding)標”作(zuo)校準可不可以?
涂植(zhi)光教授(shou)主編的(de)《臨床檢驗生物化學》在“臨床生物化學自動分(fen)析(xi)析(xi)方(fang)法”(P.364)中(zhong)提(ti)及(ji)“分(fen)析(xi)儀器測(ce)定方(fang)法基(ji)本上(shang)都需要(yao)校(xiao)準(zhun)(zhun)(Calibration),也(ye)稱定標,因為分(fen)光光度法可以看成是比例(li)光度法。”同(tong)時(shi)在標準(zhun)(zhun)液(ye)(ye)(ye)個(ge)數(shu)及(ji)濃(nong)度時(shi)又說“校(xiao)準(zhun)(zhun)曲線線性(xing)好并通(tong)過坐標零點(dian)(dian),可采用一個(ge)校(xiao)準(zhun)(zhun)液(ye)(ye)(ye);線性(xing)好的但不通(tong)過坐標零點(dian)(dian),應使(shi)用兩個(ge)以上(shang)的校(xiao)準(zhun)(zhun)液(ye)(ye)(ye)。對于校(xiao)準(zhun)(zhun)曲線呈非(fei)線性(xing)者,必須使(shi)用3個(ge)以上(shang)校(xiao)準(zhun)(zhun)液(ye)(ye)(ye),每(mei)一個(ge)校(xiao)準(zhun)(zhun)液(ye)(ye)(ye)都有一個(ge)合適的濃(nong)度”。著者后面也(ye)談(tan)及(ji)校(xiao)準(zhun)(zhun)核查。
馮仁豐教授(shou)在從玉(yu)隆教授(shou)主編《臨床(chuang)實驗室管理》第四章(zhang)“臨床檢驗質量管理技術基礎”(P.62)大多數檢驗(yan)室又(you)習慣以單一標準來校準結果,原(yuan)則上應(ying)在(zai)標準曲(qu)線呈(cheng)(cheng)通過(guo)原(yuan)點(dian)的(de)直線時(shi)(shi)才可作這樣的(de)處理(li)。呈(cheng)(cheng)不通過(guo)原(yuan)點(dian)的(de)直線關系時(shi)(shi),至少應(ying)使(shi)(shi)用兩點(dian)定(ding)標;呈(cheng)(cheng)拋物曲(qu)線狀時(shi)(shi),應(ying)使(shi)(shi)用多點(dian)定(ding)標。
通過上(shang)述(shu)復習,“單(dan)定(ding)定(ding)標(biao)(biao)(biao)(biao)”作校(xiao)準(zhun)(zhun)應該是(shi)條(tiao)件(jian)的(de)(de)(de),如(ru)果廠家有關(guan)方法穩定(ding)性(xing)文件(jian)或者自(zi)建檢(jian)測系(xi)統(tong)的(de)(de)(de)評價(jia)中(zhong),已經證(zheng)(zheng)明(ming)該項目性(xing)能特點(dian)(dian)之一的(de)(de)(de)標(biao)(biao)(biao)(biao)準(zhun)(zhun)曲(qu)線(xian)是(shi)線(xian)性(xing)關(guan)系(xi),而(er)且a值幾乎(hu)為0,即Y=bX,我也(ye)(ye)認為可(ke)以用(yong)單(dan)點(dian)(dian)定(ding)標(biao)(biao)(biao)(biao)作校(xiao)準(zhun)(zhun),但(dan)可(ke)不(bu)(bu)能忘記做校(xiao)準(zhun)(zhun)驗(yan)證(zheng)(zheng)。如(ru)果某項目雖屬線(xian)性(xing),但(dan)a不(bu)(bu)等于0,即存在截(jie)距(ju),它的(de)(de)(de)方程(cheng)應該是(shi)Y=a+b1X的(de)(de)(de)話(hua),您用(yong)單(dan)點(dian)(dian)校(xiao)準(zhun)(zhun),硬把(ba)它作Y=b2X處(chu)理,既(ji)有斜率變化,也(ye)(ye)存在截(jie)距(ju)a造成(cheng)偏(pian)差(cha),用(yong)定(ding)標(biao)(biao)(biao)(biao)點(dian)(dian)A值代入(ru)兩個方程(cheng)式(shi),應該結果是(shi)一樣(yang)的(de)(de)(de),但(dan)離(li)您定(ding)標(biao)(biao)(biao)(biao)點(dian)(dian)較(jiao)遠(yuan)的(de)(de)(de)濃度(du)標(biao)(biao)(biao)(biao)本會造成(cheng)較(jiao)大偏(pian)差(cha)。截(jie)距(ju)a是(shi)正(zheng)值或負值造成(cheng)偏(pian)差(cha)也(ye)(ye)不(bu)(bu)同(tong)了(le)。如(ru)果您應用(yong)“校(xiao)準(zhun)(zhun)驗(yan)證(zheng)(zheng)”高、中(zhong)、低值校(xiao)準(zhun)(zhun)品就會發現,離(li)定(ding)標(biao)(biao)(biao)(biao)點(dian)(dian)較(jiao)遠(yuan)的(de)(de)(de)濃度(du)帶采較(jiao)大誤差(cha),同(tong)時(shi)肯定(ding)也(ye)(ye)通不(bu)(bu)過“校(xiao)準(zhun)(zhun)驗(yan)證(zheng)(zheng)”。如(ru)果某項目標(biao)(biao)(biao)(biao)準(zhun)(zhun)曲(qu)線(xian)不(bu)(bu)是(shi)線(xian)性(xing)而(er)是(shi)拋物曲(qu)線(xian),只能用(yong)多點(dian)(dian)校(xiao)準(zhun)(zhun)和校(xiao)準(zhun)(zhun)驗(yan)證(zheng)(zheng)了(le),更不(bu)(bu)能用(yong)單(dan)點(dian)(dian)定(ding)標(biao)(biao)(biao)(biao)作校(xiao)準(zhun)(zhun)。
當(dang)今我(wo)們知(zhi)道國內不少單位都(dou)是自建檢(jian)測(ce)系統,而(er)且(qie)也未對每一項目做(zuo)過(guo)性能評(ping)價,標(biao)(biao)準(zhun)曲線(xian)的(de)性質不明,如果您用(yong)單點(dian)定(ding)標(biao)(biao)作(zuo)校(xiao)準(zhun),也不做(zuo)校(xiao)準(zhun)驗證,就轉入測(ce)定(ding)標(biao)(biao)本(ben),就必然陷入我(wo)說(shuo)的(de)誤(wu)區或陷阱。所以用(yong)“單點(dian)定(ding)標(biao)(biao)”作(zuo)校(xiao)準(zhun)要注意前堤和一定(ding)要進行校(xiao)準(zhun)驗證。
三、校準品亂用十分(fen)普遍(bian),不(bu)知(zhi)道校準品有專用性
上個世紀50年代(dai)都用標(biao)準(zhun)(zhun)品或標(biao)準(zhun)(zhun)液來校(xiao)準(zhun)(zhun)檢測(ce)方法(fa),那時(shi)使(shi)用標(biao)準(zhun)(zhun)品時(shi)不(bu)強調它的專用性。后(hou)來發現這(zhe)樣做法(fa)忽視了標(biao)本和標(biao)準(zhun)(zhun)處于完全不(bu)同基質狀(zhuang)態,知道有基質和基質效應后,不(bu)宜再用(yong)(yong)(yong)(yong)(yong)(yong)標準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)液了(le),約20年前開始引用(yong)(yong)(yong)(yong)(yong)(yong)具有(you)(you)與患(huan)者樣(yang)品(pin)(pin)基質相似的(de)校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)替代標準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin),用(yong)(yong)(yong)(yong)(yong)(yong)于日常工作(zuo)以消除基質效應。但校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)具有(you)(you)專(zhuan)(zhuan)(zhuan)用(yong)(yong)(yong)(yong)(yong)(yong)性(xing),它只(zhi)(zhi)能(neng)專(zhuan)(zhuan)(zhuan)用(yong)(yong)(yong)(yong)(yong)(yong)于指定(ding)的(de)某(mou)公(gong)司型號的(de)儀器、試劑、方法和檢(jian)(jian)測(ce)程序組成的(de)檢(jian)(jian)測(ce)系(xi)統(tong),才能(neng)起校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)和溯源(yuan)作(zuo)用(yong)(yong)(yong)(yong)(yong)(yong)。所(suo)以校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)只(zhi)(zhi)能(neng)為(wei)(wei)指定(ding)的(de)檢(jian)(jian)測(ce)系(xi)統(tong)服務,不(bu)能(neng)對其(qi)他系(xi)統(tong)作(zuo)校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)用(yong)(yong)(yong)(yong)(yong)(yong)。如(ru)果用(yong)(yong)(yong)(yong)(yong)(yong)在其(qi)它檢(jian)(jian)測(ce)系(xi)統(tong)作(zuo)校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun),將會嚴(yan)重影(ying)響(xiang)檢(jian)(jian)驗質量(liang),使(shi)病人樣(yang)品(pin)(pin)的(de)檢(jian)(jian)測(ce)結果不(bu)可靠,更不(bu)具有(you)(you)溯源(yuan)性(xing)。由于部(bu)分同志對校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)專(zhuan)(zhuan)(zhuan)用(yong)(yong)(yong)(yong)(yong)(yong)性(xing)認識不(bu)足,所(suo)以校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)亂用(yong)(yong)(yong)(yong)(yong)(yong)十(shi)分普(pu)遍,我(wo)們應該(gai)及時糾正。現(xian)在最(zui)實用(yong)(yong)(yong)(yong)(yong)(yong)的(de)是利用(yong)(yong)(yong)(yong)(yong)(yong)病人新(xin)鮮標本(ben)(其(qi)實是最(zui)佳校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin))和方法學(xue)比較為(wei)(wei)基礎,實現(xian)標準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)轉移的(de)辦法。或者在自建檢(jian)(jian)測(ce)系(xi)統(tong)校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)后,將優質某(mou)批(pi)號校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)重新(xin)定(ding)靶值(zhi),然(ran)后用(yong)(yong)(yong)(yong)(yong)(yong)己建有(you)(you)新(xin)靶值(zhi)該(gai)批(pi)號校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)品(pin)(pin)來作(zuo)本(ben)自建檢(jian)(jian)測(ce)系(xi)統(tong)校(xiao)(xiao)(xiao)(xiao)(xiao)準(zhun)(zhun)(zhun)(zhun)(zhun)(zhun)用(yong)(yong)(yong)(yong)(yong)(yong),這種(zhong)做法也(ye)僅僅是過渡(du)辦法而(er)己。
雖然國(guo)(guo)外也有(you)(you)生產具有(you)(you)多個校準值的校準品,但只適應(ying)國(guo)(guo)外知名品牌的封閉檢測(ce)系(xi)統,不一(yi)定(ding)能(neng)用(yong)于(yu)我國(guo)(guo)多種多樣的自建檢測(ce)系(xi)統,何況還必須通(tong)過科學比對才能(neng)知曉可(ke)否使用(yong),當(dang)今不能(neng)解決我們(men)(men)面(mian)臨的實際問題。據悉目(mu)前國(guo)(guo)內外正試圖研發幾乎沒有(you)(you)基質效應(ying)的互通(tong)性校準品,如果獲得成功(gong)并能(neng)大(da)量供應(ying)市場,對我們(men)(men)來講將是一(yi)個好(hao)消(xiao)息。
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