[ppt]現(xiàn)場流行病學(xué)的基石病例定義

1、.,現(xiàn)場流行病學(xué)的基石 病例定義,劉 明 斌 2010年2月25日,南昌市疾病預(yù)防控制中心 中國現(xiàn)場流行病學(xué)培訓(xùn)項目,.,主要內(nèi)容Contents,為什么要使用病例定義？ Why use a case definition? 什么是病例定義？ What is a case definition? 敏感度和特異度問題 Sensitivity and specificity 構(gòu)建病例定義 Construction of case definitions 監(jiān)測系統(tǒng)病例定義應(yīng)用實例 Applying case definitions 病例一覽表 Line Listing 疾病的時間序列 Time se

2、quence of illness,.,為什么使用病例定義? Why use a case definition?,醫(yī)生、護士、實驗室和其他人員依法報告 Doctors, nurses, laboratories, and others report notifiable events 資料產(chǎn)生外在變異 Produces extraneous variability in these data 減少變異性以便： Need to minimize this variability to: 監(jiān)視趨勢 Monitor trends 評價干預(yù)效果 Evaluate the effectiveness

3、of intervention activities 地區(qū)間的比較 Compare areas 比較結(jié)果應(yīng)真實反應(yīng)疾病本身的變化和不同 Comparisons must reflect changes or differences in the disease,.,疾病監(jiān)測的病例定義必須始終保持一致Case definitions for surveillance need to be consistent over time.,報告病例數(shù) Reported Cases,年份 Quarter year,.,20052006年某社區(qū)病毒性肝炎每周報告發(fā)病率Viral Hepatitis by w

4、eek for one county, 2005-2006,乙肝 HBV,未分型肝炎 Unspecified hepatitis,.,20052006年某社區(qū)剔除社區(qū)醫(yī)院的病毒性肝炎每周報告發(fā)病率Viral Hepatitis for a county with and without one hospital, 2005-2006,剔除社區(qū)醫(yī)院,社區(qū)總報告發(fā)病率,.,病例的錯誤分類可導(dǎo)致流行病學(xué)分析偏差Misclassified cases can bias epidemiologic analysis,.,完美的病例分類則可給出不同的率Perfect classification give

5、s different rates,.,在消滅某種疾病X的過程中與其相似疾病的發(fā)病率等于10During elimination of disease X the incidence of similar disease = 10,相似疾病 Similar disease,疾病X Disease X,監(jiān)測到的疾病總數(shù) Total disease detected,.,在消滅某種疾病X的過程中與其相似疾病的發(fā)病率等于1During elimination of disease X the incidence of similar disease = 1,監(jiān)測到的病例總數(shù) Total diseas

6、e detected,疾病X Disease X,相似疾病 Similar disease,.,什么是病例定義? What is a case definition?,一套標準 A set of standard criteria 用于確定是否感染 Used to decide if a person has an infection 保證衛(wèi)生統(tǒng)計結(jié)果是真實可信的 Assures that differences in health statistics are real 根據(jù)目的不同而不同 Varies with the purpose,.,不同專家會對同一（群）病人進行相同分類嗎？Will

7、 experts classify the same patients the same?,10位專家會診100位病人 10 experts review 100 patients 每位專家均將他們劃分為某病病人或非病人 Each expert classifies them as a case or not a case of a disease X 每位專家會按同樣方法對每位病人進行分類嗎？Will every expert classify every patient the same way? Case or not a case?,.,是否可能存在完美專家？Will one expe

8、rt be perfect?,假設(shè)一位專家審閱100位病人的診療記錄 One expert reviews 100 patient records. 他將如何判定病人與非病人？ A case or not a case of a disease X? 一個月后同一專家重新審閱上述100位病人的診療記錄又將如何？ One month later the expert reviews the same 100 records. 不同專家將會用同一方法或標準判定每位病人？Will every expert classify every patient the same way? Case or no

9、t a case?,.,一個典型的病例定義（臨床診斷）：麻疹A(yù) typical case definition: measles,出皮疹37天 Generalized skin rash of 3 to 7 days duration 體溫大于38度 Fever 38C 加上以下一項或多項 Plus one or more of the following 鼻卡他癥狀 coryza (鼻塞 stuffy, 流涕 runny nose) 咳嗽 cough 結(jié)膜充血 conjunctival injection,.,敏感度和特異度Sensitivity and specificity,敏感度 Se

10、nsitivity 能夠發(fā)現(xiàn)的病例占所有真實病例的比例 of all the true cases of the disease how many (what percent or proportion) does the method discover? 特異度 Specificity 能夠發(fā)現(xiàn)的非病例占所有非病例的比例 of all the non-cases how many (what percent or proportion) does the method discover?,.,病例定義永遠不可能完美Case definitions are never perfect,.,敏感

11、度等于真實病例被準確判定的比例Sensitivity = proportion of true cases correctly identified,敏感度 Sensitivity = 90/100 = 0.90 = 90%,假陰性率Percentage false negatives = 10/100 = 0.10 = 10%,.,特異度等于非病例被準確判定的比例Specificity = the proportion of non-cases correctly identified,特異度 Specificity = 80/100 = 0.80 = 80%,假陽性率 Percentage

12、 false positives = 20/100 = 0.20 = 20%,.,假定某社區(qū)在疾病X暴發(fā)期間同時存在其它不同疾病Consider a county with different diseases during an outbreak of Disease X.,與疾病X相似 Similarity to disease X,其它疾病 Other diseases,疾病X Disease X,.,高度敏感的病例定義必將包括很多其它疾病的病例A case definition that includes all cases will include many other diseas

13、es,高度敏感的病例定義 This is called a “highly sensitive” case definition,非病例 Not Cases,.,高度特異的病例定義必將排除包括很多真實病例A case definition that includes only cases will exclude many cases,X疾病病例 Disease X,高度特異的病例定義 This is called a “highly specific” case definition,非病例 Not Cases,.,病例定義可有多個水平The case definition may have

14、 levels of certainty.,非病例 Not Cases,疑似病例 Suspect,可能病例 Possible,臨床病例 Probable,確診病例 Confirmed,特異度 Specificity,敏感度 Sensitivity,.,細菌性痢疾暴發(fā)的病例定義Case definition for a shigellosis outbreak,非病例 Not Cases,腹瀉 Diarrhea 2 days,Diarrhea 2 days +嘔吐Vomit 或者OR 發(fā)燒Fever 38C,Diarrhea 2 days +Vomit 并且AND Fever 38C,Suspe

15、ct, or Possible, or Probable +實驗室陽性Shigella,疑似病例 Suspect,可能病例 Possible,臨床病例 Probable,確診病例 Confirmed,.,敏感度和特異度可隨目標的不同而變化Variability in sensitivity and specificity depends on purpose,診斷和治療 Diagnosis and treatment of patients. 流行病學(xué)調(diào)查階段 Phase of an epidemiologic investigation 確證暴發(fā)原因 To identify cause 常規(guī)

16、監(jiān)測或疾病登記 For routine surveillance or registries 內(nèi)部或者外部使用 For internal or external use,.,暴發(fā)期間使用敏感病例定義During outbreaks the performance of a sensitive case definition improves,相似疾病,暴發(fā)疾病,疾病暴發(fā),.,構(gòu)建病例定義Construction of case definitions,.,疾病識別標志：Disease Identifiers:,癥狀 Symptomatology 體征（物理檢查） Signs (Physical

17、 examination) 臨床評價 Clinical evaluations (EKG, EEG, etc.) 不符合其他疾病 Lack of compatibility with other diseases 治療情況 Response to treatment 實驗室檢測（病毒分離、血糖等） Laboratory tests (virus isolation, blood sugar, etc.),.,流行病學(xué)標準Epidemiologic criteria,時間 Time 地點 Place 人 Person 宿主因素（基礎(chǔ)疾病） Host factors (underlying ill

18、ness) 與其它病例的流行病學(xué)聯(lián)系 Linkages to other cases 相關(guān)危險因素 Associations with risk factors,.,感染性胃腸炎：病例定義示例Infectious gastroenteritis: Example case definition,臨床 Clinical: 腹瀉（3次以上稀便x2天） Diarrhea (3+ liquid stools x 2 days) 發(fā)熱 Fever 無其他原因（藥物抗生素） No other cause (drugs - antibiotics) 實驗室確診 Confirmed Laboratory: 糞

19、便中發(fā)現(xiàn)病原體 Organism identified in stool 流行病學(xué) Epidemiological 在最短潛伏期內(nèi)住院 Hospitalized for minimum incubation period 潛伏期期間在醫(yī)院 In hospital during incubation,.,使用一個大多數(shù)或全部病例具有的癥狀特征Use one characteristic that will include most or all cases,腹瀉 Diarrhea 發(fā)熱 Fever 黃疸 Jaundice 出疹 Rash 出疹并發(fā)熱 Rash+fever 咳嗽并發(fā)熱 Cough

20、+ fever,.,使用在某些病例中發(fā)現(xiàn)的更具特異性的癥狀特征Use more specific characteristics that are seen in some cases,特殊發(fā)現(xiàn) Specific findings 楊梅舌猩紅熱 Strawberry tongue - scarlet fever 特殊病癥 Pathognomonic finding 柯氏斑麻疹 Koplicks spots = measles,.,使用一組一般性的癥狀特征Use a group of common findings,卡他癥狀 Coryza 咳嗽 Cough 結(jié)膜炎 Conjunctivitis,

21、.,其它標準Other criteria,不能被其它已知疾病所能解釋的癥狀 Symptoms not explained by another confirmed disease or condition 既往健康人所具有的特征 In a previously healthy person,.,川崎病Kawasaki disease,發(fā)熱持續(xù)5天或以上 Febrile illness for 5 or more days 并同時具有以下5種癥狀中的4種 With four of the following five findings 雙眼結(jié)膜充血 Bilateral conjunctival

22、injection 新發(fā)口腔粘膜破損 Oral lesions (new) 手指和腳趾破損 Lesions on fingers and toes 皮疹 Skin rash 頸部淋巴結(jié)病 Cervical lymphadenopathy,.,新生兒破傷風(fēng)Neonatal Tetanus,新生兒 Neonate who 出生時啼哭 Cried at birth 出生后頭兩天內(nèi)能正常吸允 Had normal suck for first 2 days of life 出生后第3天至30天以內(nèi) Developed from 3 to 30 days after birth 無力吸允 Inabili

23、ty to suck 出現(xiàn)痙攣 Generalized spasticity 可有驚厥 With or without convulsions 死亡 Commonly results in death,.,百日咳Pertussis,咳嗽并具有以下任一特征 Cough with one of the following characteristics 咳嗽持續(xù)2周或2周以上 Continues for 2 or more weeks 陣發(fā) With paroxysms 咳嗽后嘔吐 Posttussive vomiting,.,病例定義應(yīng)用實例Applying case definitions,.

24、,舉例：人狂犬病監(jiān)測病例定義的標準Example criteria for a case definition for human rabies for surveillance,臨床標準 Clinical: 腦炎 Encephalitis 發(fā)病后10天內(nèi)死亡 Death within 10 days of onset 實驗室標準 Laboratory: 頭發(fā)毛囊、角膜或者腦組織免疫熒光抗體染色陽性 Direct FA of hair follicle, cornea or brain 抗狂犬病毒IgG或IgM抗體陽性（未經(jīng)免疫者） Anti-rabies IgG or IgM in an u

25、nvaccinated person 流行病學(xué)標準 Epidemiological: 被已知宿主動物咬傷 Bite from a known reservoir animal species 被患狂犬病的動物咬傷 Bite from a rabid animal,.,舉例：狂犬病病例定義Example rabies case definition,疑似病例 Suspect 患腦炎并于10天內(nèi)死亡 Encephalitis with death in 10 days 可能病例 = 疑似病例 Possible = suspect and 動物咬傷 animal bite 臨床診斷病例 = 疑似病例

26、 Probable = suspect and 被患狂犬病的動物咬傷 bite from rabid animal 確診病例 =疑似病例、可能病例或者臨床診斷病例 Confirmed = suspect, possible or probable 免疫熒光抗體檢測狂犬病毒 陽性 Rabies virus by direct FA from cornea, hair follicle, or brain 或者抗狂犬病毒IgM抗體陽性（未經(jīng)免疫者） Or anti-rabies IgM in an unvaccinated person,.,根據(jù)以下報告的狂犬病例數(shù)據(jù)，哪些病例符合病例定義？Som

27、e data from reported rabies cases. Which fit the case definitions?,E=腦炎encephalitis Y = 是Yes N = 否No R =患狂犬病的動物 Rabid Animal,O= 其它動物 other animal ND =沒有檢測 Not done CI = 角膜印跡Corneal Impression Br = 腦組織 Brain,.,腮腺炎性腦膜腦炎Mumps meningoencephalitis,臨床標準 Clinical 腦膜炎或腦炎癥狀并發(fā)熱大于37.5度 Symptoms of meningitis o

28、r encephalitis with fever (37.5 C) 腦脊液白細胞計數(shù)大于50個/ml、葡萄糖大于3,0 um/L CSF with 50 leucocytes/ml y glucose 3,0 um/L 前2周內(nèi)患有流行性腮腺炎 Mumps disease within 2 weeks before 流行病學(xué)標準 Epidemiologic 發(fā)病前一個月與流行性腮腺炎患者面對面接觸 過 Face-to-face contact with a mumps case in the month before onset 實驗室確診 標準 Laboratory confirmatio

29、n 抗腮腺炎病毒IgM抗體 Anti-mumps IgM 分離到腮腺炎病毒 Isolation of mumps virus,.,流行性腮腺炎性腦膜炎Mumps Meningitis,疑似病例 Suspect 癥狀加接觸 Symptoms plus contact 可能病例 Possible 癥狀加流行性腮腺炎 Symptoms plus mumps disease 臨床診斷病例 Probable 疑似或者可能病例加腦脊液檢查 Suspect or possible with compatible CSF 確診病例 Confirmed 上述三種病例 Suspect, possible or p

30、robable 急性期或恢復(fù)期檢測到IgM抗體或分離到腮腺炎病毒 Anti-mumps IgM or isolation of mumps virus during acute illness or convalescence,.,根據(jù)以下病例一覽表判定哪些病例符合病例定義Can you apply the case definition to this line-listing of patients?,.,病例一覽表Example of a Line Listing,1=“Yes”?=“Dont know” 0=“No”,.,如何制作一覽表How to Create a Line Listing,及時添加新的確診病例 Add new cases as they are identified 在調(diào)查過程中保持更新所有病例信息 Update case information throughout the investigation 根據(jù)情況設(shè)置變量數(shù)量 Number of variables to i