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1、现场流行病学的基石病例定义,刘 明 斌2010年2月25日,南昌市疾病预防控制中心中国现场流行病学培训项目,主要内容Contents,为什么要使用病例定义？Why use a case definition?什么是病例定义？What is a case definition?敏感度和特异度问题 Sensitivity and specificity构建病例定义 Construction of case definitions监测系统病例定义应用实例 Applying case definitions病例一览表 Line Listing疾病的时间序列 Time sequence of illne
2、ss,为什么使用病例定义?Why use a case definition?,医生、护士、实验室和其他人员依法报告 Doctors,nurses,laboratories,and others report notifiable events 资料产生外在变异 Produces extraneous variability in these data减少变异性以便：Need to minimize this variability to:监视趋势 Monitor trends评价干预效果 Evaluate the effectiveness of intervention activitie
3、s地区间的比较 Compare areas比较结果应真实反应疾病本身的变化和不同 Comparisons must reflect changes or differences in the disease,疾病监测的病例定义必须始终保持一致Case definitions for surveillance need to be consistent over time.,报告病例数Reported Cases,年份Quarter year,20052006年某社区病毒性肝炎每周报告发病率Viral Hepatitis by week for one county,2005-2006,乙肝HB
4、V,未分型肝炎Unspecified hepatitis,20052006年某社区剔除社区医院的病毒性肝炎每周报告发病率Viral Hepatitis for a county with and without one hospital,2005-2006,剔除社区医院,社区总报告发病率,病例的错误分类可导致流行病学分析偏差Misclassified cases can bias epidemiologic analysis,完美的病例分类则可给出不同的率Perfect classification gives different rates,在消灭某种疾病X的过程中与其相似疾病的发病率等于1
5、0During elimination of disease X the incidence of similar disease=10,相似疾病Similar disease,疾病XDisease X,监测到的疾病总数Total disease detected,在消灭某种疾病X的过程中与其相似疾病的发病率等于1During elimination of disease X the incidence of similar disease=1,监测到的病例总数Total disease detected,疾病XDisease X,相似疾病Similar disease,什么是病例定义?Wha
6、t is a case definition?,一套标准 A set of standard criteria用于确定是否感染 Used to decide if a person has an infection保证卫生统计结果是真实可信的 Assures that differences in health statistics are real 根据目的不同而不同 Varies with the purpose,不同专家会对同一（群）病人进行相同分类吗？Will experts classify the same patients the same?,10位专家会诊100位病人 10 e
7、xperts review 100 patients 每位专家均将他们划分为某病病人或非病人 Each expert classifies them as a case or not a case of a disease X每位专家会按同样方法对每位病人进行分类吗？Will every expert classify every patient the same way?Case or not a case?,是否可能存在完美专家？Will one expert be perfect?,假设一位专家审阅100位病人的诊疗记录 One expert reviews 100 patient re
8、cords.他将如何判定病人与非病人？A case or not a case of a disease X?一个月后同一专家重新审阅上述100位病人的诊疗记录又将如何？One month later the expert reviews the same 100 records.不同专家将会用同一方法或标准判定每位病人？Will every expert classify every patient the same way?Case or not a case?,一个典型的病例定义（临床诊断）：麻疹A typical case definition:measles,出皮疹37天 Gener
9、alized skin rash of 3 to 7 days duration体温大于38度 Fever 38C加上以下一项或多项 Plus one or more of the following鼻卡他症状 coryza(鼻塞 stuffy,流涕 runny nose)咳嗽 cough结膜充血 conjunctival injection,敏感度和特异度Sensitivity and specificity,敏感度 Sensitivity 能够发现的病例占所有真实病例的比例 of all the true cases of the disease how many(what percent
10、 or proportion)does the method discover?特异度 Specificity 能够发现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?,病例定义永远不可能完美Case definitions are never perfect,敏感度等于真实病例被准确判定的比例Sensitivity=proportion of true cases correctly identified,敏感度 Sensitivity=90/100
11、=0.90=90%,假阴性率Percentage false negatives=10/100=0.10=10%,特异度等于非病例被准确判定的比例Specificity=the proportion of non-cases correctly identified,特异度 Specificity=80/100=0.80=80%,假阳性率 Percentage false positives=20/100=0.20=20%,假定某社区在疾病X暴发期间同时存在其它不同疾病Consider a county with different diseases during an outbreak of
12、 Disease X.,与疾病X相似 Similarity to disease X,其它疾病Otherdiseases,疾病XDisease X,高度敏感的病例定义必将包括很多其它疾病的病例A case definition that includes all cases will include many other diseases,高度敏感的病例定义This is called a“highly sensitive”case definition,非病例NotCases,高度特异的病例定义必将排除包括很多真实病例A case definition that includes only
13、cases will exclude many cases,X疾病病例Disease X,高度特异的病例定义This is called a“highly specific”case definition,非病例NotCases,病例定义可有多个水平The case definition may have levels of certainty.,非病例NotCases,疑似病例Suspect,可能病例Possible,临床病例Probable,确诊病例Confirmed,特异度 Specificity,敏感度 Sensitivity,细菌性痢疾暴发的病例定义Case definition f
14、or a shigellosis outbreak,非病例NotCases,腹泻Diarrhea 2 days,Diarrhea 2 days+呕吐Vomit 或者OR 发烧Fever 38C,Diarrhea 2 days+Vomit 并且AND Fever 38C,Suspect,orPossible,orProbable+实验室阳性Shigella,疑似病例Suspect,可能病例Possible,临床病例Probable,确诊病例Confirmed,敏感度和特异度可随目标的不同而变化Variability in sensitivity and specificity depends o
15、n purpose,诊断和治疗 Diagnosis and treatment of patients.流行病学调查阶段 Phase of an epidemiologic investigation确证暴发原因 To identify cause常规监测或疾病登记 For routine surveillance or registries内部或者外部使用 For internal or external use,暴发期间使用敏感病例定义During outbreaks the performance of a sensitive case definition improves,相似疾病,
16、暴发疾病,疾病暴发,构建病例定义Construction of case definitions,疾病识别标志：Disease Identifiers:,症状 Symptomatology体征（物理检查）Signs(Physical examination)临床评价 Clinical evaluations(EKG,EEG,etc.)不符合其他疾病 Lack of compatibility with other diseases治疗情况 Response to treatment实验室检测（病毒分离、血糖等）Laboratory tests(virus isolation,blood sug
17、ar,etc.),流行病学标准Epidemiologic criteria,时间 Time地点 Place人 Person宿主因素（基础疾病）Host factors(underlying illness)与其它病例的流行病学联系 Linkages to other cases相关危险因素 Associations with risk factors,感染性胃肠炎：病例定义示例Infectious gastroenteritis:Example case definition,临床 Clinical:腹泻（3次以上稀便x2天）Diarrhea(3+liquid stools x 2 days)
18、发热 Fever无其他原因（药物抗生素）No other cause(drugs-antibiotics)实验室确诊 Confirmed Laboratory:粪便中发现病原体 Organism identified in stool流行病学 Epidemiological在最短潜伏期内住院 Hospitalized for minimum incubation period潜伏期期间在医院 In hospital during incubation,使用一个大多数或全部病例具有的症状特征Use one characteristic that will include most or all
19、cases,腹泻 Diarrhea发热 Fever黄疸 Jaundice出疹 Rash出疹并发热 Rash+fever咳嗽并发热 Cough+fever,使用在某些病例中发现的更具特异性的症状特征Use more specific characteristics that are seen in some cases,特殊发现 Specific findings杨梅舌猩红热 Strawberry tongue-scarlet fever特殊病症 Pathognomonic finding柯氏斑麻疹 Koplicks spots=measles,使用一组一般性的症状特征Use a group o
20、f common findings,卡他症状 Coryza咳嗽 Cough结膜炎 Conjunctivitis,其它标准Other criteria,不能被其它已知疾病所能解释的症状 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,发热持续5天或以上 Febrile illness for 5 or more days并同时具有以下5种症状中的4种 With four of the foll
21、owing five findings双眼结膜充血 Bilateral conjunctival injection新发口腔粘膜破损 Oral lesions(new)手指和脚趾破损 Lesions on fingers and toes皮疹 Skin rash颈部淋巴结病 Cervical lymphadenopathy,新生儿破伤风Neonatal Tetanus,新生儿 Neonate who 出生时啼哭 Cried at birth出生后头两天内能正常吸允 Had normal suck for first 2 days of life出生后第3天至30天以内 Developed fr
22、om 3 to 30 days after birth无力吸允 Inability to suck出现痉挛 Generalized spasticity可有惊厥 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咳嗽持续2周或2周以上 Continues for 2 or more weeks阵发 With paroxysms咳嗽后呕吐 Posttussive vomiting,病例定义应用
23、实例Applying case definitions,举例：人狂犬病监测病例定义的标准Example criteria for a case definition for human rabies for surveillance,临床标准 Clinical:脑炎 Encephalitis发病后10天内死亡 Death within 10 days of onset实验室标准 Laboratory:头发毛囊、角膜或者脑组织免疫荧光抗体染色阳性 Direct FA of hair follicle,cornea or brain抗狂犬病毒IgG或IgM抗体阳性（未经免疫者）Anti-rabie
24、s IgG or IgM in an unvaccinated person流行病学标准 Epidemiological:被已知宿主动物咬伤 Bite from a known reservoir animal species被患狂犬病的动物咬伤 Bite from a rabid animal,举例：狂犬病病例定义Example rabies case definition,疑似病例 Suspect患脑炎并于10天内死亡 Encephalitis with death in 10 days可能病例=疑似病例 Possible=suspect and 动物咬伤 animal bite临床诊断病
25、例=疑似病例 Probable=suspect and被患狂犬病的动物咬伤 bite from rabid animal确诊病例=疑似病例、可能病例或者临床诊断病例 Confirmed=suspect,possible or probable免疫荧光抗体检测狂犬病毒 阳性 Rabies virus by direct FA from cornea,hair follicle,or brain或者抗狂犬病毒IgM抗体阳性（未经免疫者）Or anti-rabies IgM in an unvaccinated person,根据以下报告的狂犬病例数据，哪些病例符合病例定义？Some data fr
26、om reported rabies cases.Which fit the case definitions?,E=脑炎encephalitisY=是YesN=否NoR=患狂犬病的动物 Rabid Animal,O=其它动物 other animalND=没有检测 Not doneCI=角膜印迹Corneal ImpressionBr=脑组织 Brain,腮腺炎性脑膜脑炎Mumps meningoencephalitis,临床标准 Clinical脑膜炎或脑炎症状并发热大于37.5度 Symptoms of meningitis or encephalitis with fever(37.5
27、 C)脑脊液白细胞计数大于50个/ml、葡萄糖大于3,0 um/L CSF with 50 leucocytes/ml y glucose 3,0 um/L前2周内患有流行性腮腺炎 Mumps disease within 2 weeks before流行病学标准 Epidemiologic发病前一个月与流行性腮腺炎患者面对面接触 过 Face-to-face contact with a mumps case in the month before onset实验室确诊 标准 Laboratory confirmation 抗腮腺炎病毒IgM抗体 Anti-mumps IgM 分离到腮腺炎病
28、毒 Isolation of mumps virus,流行性腮腺炎性脑膜炎Mumps Meningitis,疑似病例 Suspect症状加接触 Symptoms plus contact可能病例 Possible症状加流行性腮腺炎 Symptoms plus mumps disease临床诊断病例 Probable疑似或者可能病例加脑脊液检查 Suspect or possible with compatible CSF确诊病例 Confirmed上述三种病例 Suspect,possible or probable急性期或恢复期检测到IgM抗体或分离到腮腺炎病毒 Anti-mumps IgM
29、 or isolation of mumps virus during acute illness or convalescence,根据以下病例一览表判定哪些病例符合病例定义Can you apply the case definition to this line-listing of patients?,病例一览表Example of a Line Listing,1=“Yes”?=“Dont know”0=“No”,如何制作一览表How to Create a Line Listing,及时添加新的确诊病例 Add new cases as they are identified在调查
30、过程中保持更新所有病例信息 Update case information throughout the investigation根据情况设置变量数量 Number of variables to include will vary变量少利于目测 Fewer will allow for quick visual assessment变量多则对评估和描述暴发十分有用 More will be useful for assessment and characterization of outbreak,病例一览表应该包含的项目What should a line listing of case
31、s include?,病例姓名或身份识别号码 Case name or identifying number症状出现日期（或采样日期）Date of symptom onset(or specimen collection date)病例定义的组成要素 Components of case definition接触信息 Contact information此外还应 包括 May also include additional information such as:性别、年龄、种族、职业、危险因素 Age,gender,race,occupation,risk factors,疾病的时间序列
32、Time sequence of illness,易感 Susceptibility暴露 Exposure潜伏期 Latency,incubation,induction前驱症状 Prodrome亚临床期 Subclinical state临床期 Clinically apparent disease-appearance of recognizable symptoms致残，死亡 Incapacity convalescence,death,感染性疾病的典型时间序列Typical time sequence of an infectious disease,Prodrome,Clinical Illness,Convalescence,Relapse or Recrudesence,Incubation,暴露Exposure,发病Onset,Onset,死亡Death,恢复Recovery,时间 Time,致残 Incapacity,确诊Diagnosis,Latent State,复发,Thank you!Any Questions?,
