Prevalence和Incidence这两个词常在文献中出现，它们是什么意思，又有什么区别呢？ 1）患病率（prevalence） 也称现患率。指某特定时间内总人口中某病新旧病例所占比例。可按观察时间的不同分为： 期间患病率（period prevalence） = 某观察期间一定人群中现患某病的新旧病例数/同期的平均人口数(或被观察人数) × K 时点患病率（point prevalence） = 某一时点一定人群中现患某病新旧病例数/该时点人口数(或被观察人数) × K K = 100%，1000‰，或10000/万等。 注意，期间患病率实际上等于某一特定期间开始时患病率加上该期间内的发病率（incidence）。 2）发病率（incidence） 发病率指在一定期间内，一定人群中某病新发生的病例出现的频率。是反映疾病对人群健康影响和描述疾病分布状态的一项测量指标。 发病率 =（某时期内某人群中某病新病例人数/同时期内暴露人口数）× K K = 100%、1000‰、10000/万等。 3）二者的区别 患病率的分子为特定时间一定人群中某病新旧病例数，不管它是新发病还是旧病，只要是特定时间内疾病尚未痊愈，就记为病例数。而发病率的分子为一定期间暴露人群中新病例人数，暴露人群中任何人新发生某疾病都称为“新病例”。 患病率是由横断面调查获得的疾病频率，通常用来反映病程较长的慢性病的流行情况及其对人群健康的影响程度。而发病率是由发病报告或队列研究获得的疾病频率，通常用来反映新发生病例的出现情况。 4）二者的联系 患病率取决于两个因素，即发病率和病程。当某地某病的发病率和病程在相当长的时间内保持稳定时，患病率、发病率和病程三者的关系如下： 患病率=发病率×病程 明白没？且看看下面这个例子： 好了，一起来看看这句话—— Chronic wounds mostly affect people over the age of 60. The incidence is 0.78% of the population and the prevalence ranges from 0.18 to 0.32% ——是不是理解了呢？ 请扫描下面的二维码关注 “ 整形与修复重建外科 ” 微信公众号以获得更多关于组织再生、 整形与修复重建外科的资讯。
Prevalence and Incidence （The differences and Significances of Prevalence and Incidence） Prevalence is a frequently used epidemiological measure of how commonly adisease or condition occurs in a population. Prevalence measures how much ofsome disease or condition there is in a population at a particular point intime. The prevalence is calculated by dividing the number of persons with thedisease or condition at a particular time point by the number of individualsexamined. For example, in the study above 6139 individuals completed thequestionnaire (were examined). Of these 6139 people, 519 currently sufferedincontinence and so had the condition at the particular time point of thestudy. Thus the prevalence of incontinence was 519/6139 = 0.085. Prevalence isoften expressed as a percentage, calculated by multiplying the ratio by 100.The above study expresses prevalence as a percentage, thus the prevalence ofincontinence is 8.5% (or rounded is 9%). Another common way of expressing prevalence, particularly if theprevalence is low, is as the number of cases per 100,000 of the population. Forexample, it is easier to state the result as `66 cases per 100,000 people' thanto say the prevalence is 0.00066. Le and Boen (1995) provide further examplesof the calculation of prevalence. The incidence of a disease is another epidemiological measure. Incidencemeasures the rate of occurrence of new cases of a disease or condition.Incidence is calculated as the number of new cases of a disease or condition ina special time period (usually a year) divided by the size of the populationunder consideration who are initially disease free. For example, the incidence of meningitis in the UK in 1999 couldbe calculated by ®nding the number of new meningitis cases registered during1999 and dividing that number by the population of the UK. As this incidencerate would be very small again we tend to consider number of cases per 100,000people. Incidenceproportion (also known as cumulative incidence) is the number of new caseswithin a specified time period divided by the size of the population initiallyat risk. For example, if a population initially contains 1,000 non-diseasedpersons and 28 develop a condition over two years of observation, the incidenceproportion is 28 cases per 1,000 persons, i.e. 2.8%. Theincidence rate is the number of new cases per population in a given timeperiod. When the denominator is the sum of the person-time of the at riskpopulation, it is also known as the incidence density rate or person-timeincidence rate. Inthe same example as above, the incidence rate is 14 cases per 1000 person-years,because the incidence proportion (28 per 1,000) is divided by the number ofyears (two). Using person-time rather than just time handles situations wherethe amount of observation time differs between people, or when the populationat risk varies with time. Use of this measure implicitly implies the assumptionthat the incidence rate is constant over different periods of time, such thatfor an incidence rate of 14 per 1000 persons-years, 14 cases would be expectedfor 1000 persons observed for 1 year or 50 persons observed for 20 years. Whenthis assumption is substantially violated, such as in describing survival afterdiagnosis of metastatic cancer, it may be more useful to present incidence datain a plot of cumulative incidence over time, taking into account loss tofollow-up, using a Kaplan-Meier Plot. Considerthe following example. Say you are looking at a sample population of 225people, and want to determine the incidence rate of developing HIV over a 10year period. At the beginning of the study (t=0) you find 25 cases of existingHIV. You follow-up at 5 years (t=5 yrs) and find 20 new cases of HIV. You againfollow-up at the end of the study (t=10 years) and find 30 new cases. If youwere to measure prevalence you would simply take the total number of cases (25+ 20 + 30 = 75) and divide by your sample population (225). So prevalence wouldbe 75/225 = 0.33 or 33%. This tells you how widespread HIV is in your samplepopulation, but little about the actual risk of developing HIV. To measure incidenceyou must take into account how many years each person contributed to the study,and when they developed HIV. When it is not known exactly when a persondevelops the disease in question, epidemiologists frequently use the actuarialmethod, and assume it was developed at a half-way point between follow-ups. Forexample, at 5 years you found 20 new cases, so you assume they developed HIV at2.5 years, thus contributing (20 * 2.5) =50 person-years. At 10 years you found30 new cases. These people did not have HIV at 5 years, but did at 10, so youassume they were infected at 7.5 years, thus contributing (30 * 7.5)= 225person-years. That is a total of (225 + 50)= 275 person years so far. You alsowant to account for the 150 people who never had or developed HIV over the 10year period, (150 * 10) contributing 1500 person-years. That is a total of(1500 + 275) =1775 person-years. Now take the 50 new cases of HIV, and divideby 1775 to get 0.028, or 28 cases of HIV per 1000 population, per year. Inother words, if you were to follow 1000 people for one year, you would see 28new cases of HIV. This is a much more accurate measureof risk than prevalence. Incidence vs. prevalence Incidenceshould not be confused with prevalence which is a measure of the total numberof cases of disease in a population rather than the rate of occurrence of newcases. Thus, incidence conveys information about the risk of contracting thedisease, whereas prevalence indicates how widespread the disease is. Prevalenceis the ratio of the total number of cases in the total population and is more ameasure of the burden of the disease on society. Prevalence can also bemeasured with respect to a specific subgroup of a population (see: denominatordata). Incidence is usually more useful than prevalence in understanding thedisease etiology: for example, if incidence rate of population of a diseaseincreases, then there is a risk factor that promotes the incidence. Forexample, consider a disease that takes a long time to cure and was widespreadin 2002 but dissipated in 2003. This disease will have both high incidence andhigh prevalence in 2002, but in 2003 it will have a low incidence yet willcontinue to have a high prevalence (because it takes a long time to cure, sothe fraction of affected individuals remains high). In contrast, a disease thathas a short duration may have a low prevalence and a high incidence. Whenthe incidence is approximately constant for the duration of the disease,prevalence is approximately the product of disease incidence and averagedisease duration, so prevalence =incidence x duration (P=ID) . Theimportance of this equation is the relation between prevalence and incidence;for example, when the incidence increases, then the prevalence must alsoincrease. Whenstudying the etiology of a disease, it is better to analyze incidence ratherthan prevalence since incidence considers the duration of a condition ratherthan providing a measure of risk alone. Data source: http://blog.sina.com.cn/ouandyin Arranged by YoungyaoWang
每年的2月的最后一天是国际罕见病日。罕见病是指发病率极低、很少见的疾病，目前确认的罕见病有六七千种，约占人类疾病的10%。约有80%的罕见病是遗传缺陷所致，其中一半患者在出生时或者儿童期即可发病。目前我国罕见病防治比较落后，误诊率高，费用负担沉重，患者确诊平均要看超过5个医生。 【罕见疾病无国界】 国际罕见病日由欧洲罕见病组织于2008年2月29日发起，以四年一次的日子意寓罕见病之“罕见”，自2009年起将每年2月的最后一天定为国际罕见病日。2013年的主题是“罕见疾病无国界”。你不孤独，爱不罕见，关注罕见病，我们简单的参与，可以带给他们巨大的温暖！ http://t.cn/zYjPyjr 这个病，我也没有好办法，肿瘤就只能手术了。 检索分析用词 RareDisease 检索结果Results:147052篇 分析平台 http://pubmedpro.cn/?term=%20Rare%20Disease http://www.gopubmed.org/web/gopubmed/1?WEB0fyuvjqgch8orIeIpI0 文献分析结果如下 Top 20 of 1. rare disease browse it with it or it without it 9365 2. differential diagnosis browse it with it or it without it 7150 3. magnetic resonance browse it with it or it without it 5660 4. nervous system browse it with it or it without it 3910 5. risk factors browse it with it or it without it 3570 6. bone marrow browse it with it or it without it 3445 7. abdominal pain browse it with it or it without it 3243 8. early diagnosis browse it with it or it without it 2761 9. lymph node browse it with it or it without it 2741 10. case reports browse it with it or it without it 2559 11. heart disease browse it with it or it without it 2442 12. coronary artery browse it with it or it without it 2378 13. lymph nodes browse it with it or it without it 2326 14. renal failure browse it with it or it without it 1996 15. rare diseases browse it with it or it without it 1802 16. spinal cord browse it with it or it without it 1752 17. in vitro browse it with it or it without it 1693 18. breast cancer browse it with it or it without it 1614 19. heart failure browse it with it or it without it 1525 20. gastrointestinal tract browse it with it or it without it 1403 Top 20 of Mesh Full 1. Tomography, X-Ray Computed* browse it with it or it without it 13128 2. Mutation* browse it with it or it without it 9003 3. Skin Diseases/pathology browse it with it or it without it 8108 4. Genetic Predisposition to Disease* browse it with it or it without it 3889 5. Brain/pathology browse it with it or it without it 3286 6. Adenocarcinoma/pathology browse it with it or it without it 3094 7. Anti-Bacterial Agents/therapeutic use browse it with it or it without it 2908 8. Antineoplastic Combined Chemotherapy Protocols/therapeutic use browse it with it or it without it 2626 9. Antineoplastic Agents/therapeutic use browse it with it or it without it 2355 10. Mutation/genetics browse it with it or it without it 1975 11. Skin/pathology browse it with it or it without it 1881 12. Skin Neoplasms/pathology browse it with it or it without it 1866 13. Immunosuppressive Agents/therapeutic use browse it with it or it without it 1623 14. Breast Neoplasms/pathology browse it with it or it without it 1141 15. Magnetic Resonance Imaging/methods browse it with it or it without it 1132 16. Gastrointestinal Hemorrhage/etiology browse it with it or it without it 1116 17. Lung Neoplasms/pathology browse it with it or it without it 1107 18. Liver/pathology browse it with it or it without it 1104 19. Lung/pathology browse it with it or it without it 1073 20. Lymph Nodes/pathology browse it with it or it without it 1006 Top 20 of Year 1. 2011 browse it with it or it without it 11795 2. 2012 browse it with it or it without it 11295 3. 2010 browse it with it or it without it 10893 4. 2009 browse it with it or it without it 9995 5. 2008 browse it with it or it without it 9644 6. 2007 browse it with it or it without it 8728 7. 2006 browse it with it or it without it 8149 8. 2005 browse it with it or it without it 7087 9. 2004 browse it with it or it without it 6292 10. 2003 browse it with it or it without it 5882 11. 2002 browse it with it or it without it 5218 12. 2001 browse it with it or it without it 4673 13. 2000 browse it with it or it without it 4451 14. 1999 browse it with it or it without it 4012 15. 1998 browse it with it or it without it 3989 16. 1997 browse it with it or it without it 3664 17. 1996 browse it with it or it without it 3398 18. 1995 browse it with it or it without it 3187 19. 1994 browse it with it or it without it 2907 20. 1993 browse it with it or it without it 2769 Top Years Publications 2012 10,974 2011 10,268 2010 9,589 2009 8,741 2008 8,618 2007 7,935 2006 7,585 2005 6,705 2004 6,135 2003 5,786 2002 5,133 2001 4,636 2000 4,453 1999 1,832 2013 1,205 1998 145 1997 22 1 2 3 ... 10 Top Countries Publications United States 21,135 Japan 7,000 Germany 6,657 Italy 5,896 United Kingdom 5,737 France 5,580 Turkey 4,029 India 3,829 China 2,700 Spain 2,631 South Korea 2,266 Canada 2,091 Taiwan 1,869 Brazil 1,778 Netherlands 1,535 Greece 1,507 Australia 1,409 Switzerland 1,320 Israel 1,131 Belgium 1,046 1 2 3 ... 10 1 2 3 ... 176 Top Cities Publications London 1,720 Paris 1,624 New York City 1,594 Seoul 1,249 Ankara 1,230 Boston 1,179 Tokyo 1,166 Roma 937 Taipei 912 İstanbul 869 Houston 869 Athens 775 Milano 701 New Delhi 696 Philadelphia 690 Bethesda 668 Baltimore 662 Madrid 659 Rochester 632 Beijing 612 1 2 3 ... 176 1 2 3 ... 260 Top Journals Publications J Pediatr Surg 579 Ann Thorac Surg 451 J Med Case Reports 393 Intern Med 387 Am J Surg Pathol 376 World J Gastroentero 370 Plos One 367 J Am Acad Dermatol 360 J Laryngol Otol 357 Bmj Case Rep 335 Am J Med Genet A 321 Urology 299 Presse Med 294 Ann Dermatol Vener 293 Cancer 284 Pediatr Dermatol 274 Blood 267 Rev Med Interne 260 Surg Today 258 Spine 258 1 2 3 ... 260 1 2 3 ... 1816 Top Terms Publications Humans 86,423 Patients 60,963 Diagnosis 39,445 Adult 34,435 Middle Aged 28,289 Aged 19,099 Neoplasms 17,307 Syndrome 15,451 Child 15,351 Diagnosis, Differential 14,512 Rare Diseases 13,441 Recurrence 13,056 Women 12,905 Genes 12,405 Surgery 12,016 Treatment Outcome 11,670 Adolescent 11,588 Evaluation Studies as Topic 11,329 Mutation 10,331 Biopsy 10,247 1 2 3 ... 1816 publications over time world map http://www.gopubmed.org/web/gopubmed/1?WEB0fyuvjqgch8orIeIpI0 参考文献： 我国罕见病患者近千万 面临高误诊高漏诊困境 戈谢氏病、法布雷病、庞贝病……这些疾病虽罕见，却无不危及患者生命。记者2月24日从第一届北京罕见病学术大会获悉，我国罕见病患者近千万，他们面临着高误诊高漏诊、用药难用药贵的困境。 世界卫生组织将罕见病定义为患病人数占总人口0.65‰至1‰之间的疾病或病变。目前确认的罕见病有六七千种，约占人类疾病的10％。约有80％的罕见病是遗传缺陷所致，其中一半患者在出生时或者儿童期即可发病。目前只有不到1％的罕见病已有有效治疗方法。 http://news.sciencenet.cn/htmlnews/2013/2/274994.shtm 罕见病，是指盛行率低、少见的疾病，在美国罕见疾病组织所公布的罕见疾病高达一千种之多，在中国较为人熟知的罕见疾病包括：Fabry病、高雪氏病、黏多醣症、苯酮尿症、地中海贫血、成骨不成症(俗称玻璃娃娃)、高血氨症、有机酸血症、威尔森氏症等等。 http://www.baike.com/wiki/%E7%BD%95%E8%A7%81%E7%97%85 罕见疾病简称“罕见病”，又称“孤儿病”。顾名思义，罕见病是指患病率很低、很少见的疾病。世界卫生组织(WHO)将罕见病定义为患病人数占总人口的0.65‰-1‰之间的疾病或病变，而各国(地区)对罕见病认定的标准上存在一定差异。美国的罕见病定义是患病人数少于20万人(约占总人口的0.75‰)的疾病；日本的罕见病定义是患病人数少于5万人(约占总人口的0.4‰)的疾病；澳大利亚的定义是患病人数少于2000人(约占总人口的0.1‰)的疾病；欧盟的罕见病定义是患病率低于0.5‰的疾病。各国对罕见病的不同定义，与其对罕见病药物研发的激励政策及对罕见病诊疗费用的覆盖范围有关。 http://www.chinararedisease.cn/1-5-dingyi.html
研究进展： http://www.bioon.com/biology/postgenomics/444357.shtml NatureGentics：广东鼻咽癌患病率高从基因找原因 信息分析平台： http://www.gopubmed.org/web/gopubmed/1?WEB01jkpokpl1bysiI54I6jI00h001000j100200010 945 documents semantically analyzed 1 2 Top Years Publications 2008 68 2004 65 2003 62 2006 59 2005 58 2009 55 2007 55 2002 54 2001 48 2000 46 1998 40 1995 37 2010 34 1997 32 1999 30 1996 30 1993 20 1992 20 1994 19 1991 15 1 2 1 2 Top Countries Publications China 298 USA 135 Hong Kong 79 Taiwan 63 United Kingdom 42 Japan 36 France 27 Singapore 24 Sweden 23 Germany 23 Tunisia 19 Canada 16 Thailand 12 Malaysia 8 Italy 6 South Korea 6 Switzerland 6 Saudi Arabia 5 Greece 5 Brazil 4 1 2 1 2 3 ... 8 Top Cities Publications Changsha 112 Guangzhou 79 Hong Kong 67 Taipei 35 Chapel Hill 35 Singapur 24 London 22 Beijing 21 Stockholm 19 Toronto 15 Chengdu 13 Baltimore 12 Kowloon 12 Birmingham 11 Bethesda 11 Kanazawa 11 Bangkok 10 Villejuif 10 Monastir 9 Frederick 8 1 2 3 ... 8 1 2 3 ... 15 Top Journals Publications Int J Cancer 60 J Virol 41 Ai Zheng 39 Cancer Res 28 Oncogene 22 Clin Cancer Res 19 Cancer Lett 17 Zhonghua Zhong Liu Za Zhi 17 P Natl Acad Sci Usa 15 Chinese Med J-peking 14 Int J Oncol 14 Anticancer Res 13 J Gen Virol 13 Di Yi Jun Yi Da Xue Xue Bao 13 Cancer Genet Cytogen 11 Iarc Sci Publ 11 Virology 10 Nan Fang Yi Ke Da Xue Xue Bao 9 Am J Pathol 9 Gene Chromosome Canc 9 1 2 3 ... 15 1 2 3 ... 202 Top Terms Publications Humans 874 Nasopharyngitis 866 Carcinoma 841 Genes 755 Nasopharyngeal Neoplasms 751 nuclear pore 572 Neoplasms 448 Herpesvirus 4, Human 438 Viruses 433 Proteins 390 Cell Line 347 Patients 294 DNA 253 Polymerase Chain Reaction 238 gene expression 228 Gene Expression 225 Tissues 213 Adult 210 Animals 200 Middle Aged 196 1 2 3 ... 202 1 2 3 ... 200 Top Authors Publications Li G 41 Yao K 41 Huang D 36 Lo K 34 Raab-Traub N 25 Zhou M 24 Li X 23 Sham J 22 Tsao S 21 To K 20 Zeng Y 18 Busson P 18 Hue L 16 Tao Q 16 Lung M 15 Cao Y 15 Chen J 15 Klein G 15 Deng L 14 Furukawa M 14 1 2 3 ... 200
前两天浏览文献时，看到一篇有关精神疾病流行病学方面的文章 ，研究是以色列的精神病学家完成的，他们发现精神疾病患者的一级亲属比一般人的后代要多，并且有家族史的患者亲属的后代比没有家族史的患者亲属的后代更多，他们认为这个发现可能部分解释了为什么精神疾病会持续存在的问题。 这不由使得我想起了之前自己的一个未解的困惑精神分裂症的终生患病率为什么多年来都稳定在1％左右而没有发生变化？为什么会产生这个困惑呢，原因是精神分裂症多起病与青壮年时期，由于起病较早，患者往往还未结婚生子，我自己所见到的为数不算太多的精神分裂症患者也确实如此，而且由于患者社会功能退化加之社会对精神疾病的偏见，他们中绝大部分患病以后几乎不太可能再拥有自己的后代。而精神分裂症又是遗传度很高的疾病，遗传度可以达到85％左右。这我就迷惑了，患者已经很少后代了，这似乎是符合达尔文自然选择理论的规律，像精神分裂症这种高度遗传的精神疾病应当逐渐从人群中消失啊，为什么会一直维持稳定的患病率呢。 尽管产生了这种疑惑，但惭愧的是我并没有四处查找资料来解答，没多久也就忘记了，直到今天看到这篇文章。文章的引言部分写作的逻辑也差不多就是我之前产生困惑的逻辑顺序：精神疾病具有很高的遗传易感性，有文献支持精神疾病患者的后代要少于对照人群，那么为什么精神疾病会持续存在？这么明显的问题肯定不会到现在才有人想到，原来已经有一些解释了。 比如：存在新生突变（ de novo mutation ）；患者父母尽管未患病，但存在一些损害的印记可能会传递给除了患者以外的其他后代；还有就是精神分裂症患者的亲属的癌症患病率要低于一般对照等等。这些解释都是假设性质的。文章的作者也提出了自己的假设：患者亲属（包括未受累的父母和兄弟姐妹）的后代数会代偿性地增加。研究的结果也证实了作者的猜测。 尽管潜在的原因并不清楚，但这个现象本身已经很有意思了。不过不知道这个解释在中国是否也可行，毕竟中国实行计划生育政策已经快30年了，现在我自己作研究想找些有兄弟姐妹的精神分裂症患者都很困难（主要是在城市中的患者），既然都是独子，那就谈不上谁的后代多的问题了，不知道中国自己的流行病学调查会得到什么样的结果。我又没有那么多时间去追踪调查了，看看中国是不是很快也会有类似的研究报道出现。 说到精神分裂症这种疾病没有被自然选择掉的问题，我想到以前在三联上看到一篇专栏文章（作者是袁越），好像说精神分裂症是人类为创造性所付出的代价，由于怎么也找不到那篇文章了，记得不清楚也不敢妄谈太多了。 参考文献： Weiser M, Reichenberg A, Werbeloff N, Halperin D, Kravitz E, Yoffe R, Davidson M: Increased number of offspring in first degree relatives of psychotic individuals: a partial explanation for the persistence of psychotic illnesses. Acta Psychiatr Scand 2009; 119(6):466-71
标签: 患病率
