Unt6:疾病预后证据的分析评价 主讲教师:胡予助理教师:顾迁 授课时间:2010年3月30日(1班);2010年4月2日(2班) 、教学目的:掌握和熟悉预后评价的概念和方法 二、教学内容: 1.复习和强化循证医学的概念 2.掌握预后的概念,掌握预后的评价以及循证的过程; 3.学会设计有关预后的研究 、教学重点和难点:预后评价的各项标准,预后研究设计中的关键点。 四、中文和英文关键词 Prognosis, critical appraisal, evidence based medicine, 五、作业与思考: Assignment 1: Read the reference article by Larpacis A et al User's Guides to the medical literature V. How to use an article about prognosis, and try to understand the principles about prognosis Assignment 2: Read the article by H. Klar Yaggi et al Obstructive Sleep apnea as a risk factor for Stroke and Death Answer the following questions 1. What is the study design? 2. a)What is the study population? b) How did the author select the study population? c)Is your case similar to the study population? 3. a) How is the Osa defined?(How is the exposure defined?) b)Does the author provide a clear description of the stage of OSA? 4. Was follow up sufficiently long and complete? a)How is the follow up period defined? b)Any loss to follow up? 5. Was there adjustment for important prognostic factors? 6. a)What were the outcomes? Were objective and unbiased outcome criteria used? b) How do they get the outcomes? c) How were the outcomes ascertained? 7. What are the results? a )Ex: What is the chance of a 60-year-old, obese, Caucasian male with OSa still alive in five years? 8. Potential biases 第78页
Unit 6：疾病预后证据的分析评价 主讲教师：胡予 助理教师：顾迁 授课时间：2010 年 3 月 30 日（1 班）；2010 年 4 月 2 日（2 班） 一、教学目的：掌握和熟悉预后评价的概念和方法 二、教学内容： 1. 复习和强化循证医学的概念； 2. 掌握预后的概念，掌握预后的评价以及循证的过程； 3. 学会设计有关预后的研究。 三、教学重点和难点：预后评价的各项标准，预后研究设计中的关键点。 四、中文和英文关键词 Prognosis, critical appraisal, evidence based medicine, 五、作业与思考： Assignment 1: Read the reference article by Larpacis A et al. User’s Guides to the medical literature V. How to use an article about prognosis, and try to understand the principles about prognosis. Assignment 2: Read the article by H. Klar Yaggi et al. Obstructive Sleep Apnea as a Risk Factor for Stroke and Death Answer the following questions: 1. What is the study design? 2. a) What is the study population? b) How did the author select the study population? c) Is your case similar to the study population? 3. a) How is the OSA defined? (How is the exposure defined?) b) Does the author provide a clear description of the stage of OSA? 4. Was follow up sufficiently long and complete? a) How is the follow up period defined? b) Any loss to follow up? 5. Was there adjustment for important prognostic factors? 6. a) What were the outcomes? Were objective and unbiased outcome criteria used? b) How do they get the outcomes? c) How were the outcomes ascertained? 7. What are the results? a) Ex: What is the chance of a 60-year-old, obese, Caucasian male with OSA still alive in five years? 8. Potential biases 第 78 页
a) Are there any selection bias? Referral bias? b) Can you see any potential for misclassification of exposure? c)Can you see any potential for misclassification of outcome d) are there any selective loss to follow up? e) What factors did the author consider as potential confounders? How was the problem of confounding handled? Assignment 3 You will be divided into four groups. And each group will work as a team and design a study about the prognosis of subclinical hyperthyroidism. We' ll have two groups presenting their designs and the two groups criticizing their work Before you design the study, you can search the literatures to get some ideas about subclinical hyperthyroidism. The study design has not to be perfect, just try to consider the principles questions in prognosis Each team needs to bring a computer to the classroom. during class, you' ll have some time to discuss your study, but it's better to have an outline of your study design before you go to the class. And figure out who will present the study before class Consider the following questions: I What are the potential prognostic factors for subclinical hyperthyroidism? 2 What specific prognostic factor you want to study? What study design you want to choose? Explain it 3 Who will be your study population a)Your inclusion criteria and exclusion criteria b) How do you plan to select them? Hospital based or primary based? 4 What is your exposure( definition)? 5 What outcomes do you want to measure? How do you plan to get them and have them ascertained? 6 How long is the follow-up period? What will you do to prevent loss to follow up? 7 What association measure do you plan to use? OR, rr, hr, Kaplan-Meier curve? 8 What potential confounders do you want to adjust? 第79页
a) Are there any selection bias? Referral bias? b) Can you see any potential for misclassification of exposure? c) Can you see any potential for misclassification of outcome? d) Are there any selective loss to follow up? e) What factors did the author consider as potential confounders? How was the problem of confounding handled? Assignment 3 You will be divided into four groups. And each group will work as a team and design a study about the prognosis of subclinical hyperthyroidism. We’ll have two groups presenting their designs and the two groups criticizing their work. Before you design the study, you can search the literatures to get some ideas about subclinical hyperthyroidism. The study design has not to be perfect, just try to consider the principles questions in prognosis. Each team needs to bring a computer to the classroom. During class, you’ll have some time to discuss your study, but it’s better to have an outline of your study design before you go to the class. And figure out who will present the study before class. Consider the following questions: 1 What are the potential prognostic factors for subclinical hyperthyroidism? 2 What specific prognostic factor you want to study? What study design you want to choose? Explain it. 3 Who will be your study population? a) Your inclusion criteria and exclusion criteria. b) How do you plan to select them? Hospital based or primary based? 4 What is your exposure ( definition)? 5 What outcomes do you want to measure? How do you plan to get them and have them ascertained? 6 How long is the follow-up period? What will you do to prevent loss to follow up? 7 What association measure do you plan to use? OR, RR, HR, Kaplan-Meier curve? 8 What potential confounders do you want to adjust? 第 79 页
b) Can you see any potential for misclassification of exposure? c) Can you see any potential for misclassification of outcome? d) Are there any selective loss to follow up? e) what factors did the author consider as potential confounders? How was the problem of confounding handled? Assignment 3 You will be divided into four groups. And each group will work as a team and design study about the pro of subclinical hyperthyroidism. We' ll hav presenting their designs and the two groups criticizing their work Before you design the study, you can search the literatures to get some ideas about subclinical hyperthyroidism. The study design has not to be perfect, just try to consider the principles questions in prognosis Each team needs to bring a computer to the classroom. During class, you'll have some time to discuss your study, but it's better to have an outline of your study design before you go to the class. And figure out who will present the study before class Consider the following questions: I What are the potential prognostic factors for subclinical hyperthyroidism? 2 What specific prognostic factor you want to study? What study design you want to choose? Explain it 3 Who will be your study population? a)Your inclusion criteria and exclusion criteria b) How do you plan to select them? Hospital based or primary based? 4 What is your exposure( definition )? 5 What outcomes do you want to measure? How do you plan to get them and have 6 How long is the follow-up period? What will you do to prevent loss to follow up? 7 What association measure do you plan to use? OR, RR, Hr, Kaplan-Meier curve? 8 What potential confounders do you want to adjust 第80页
b) Can you see any potential for misclassification of exposure? c) Can you see any potential for misclassification of outcome? d) Are there any selective loss to follow up? e) What factors did the author consider as potential confounders? How was the problem of confounding handled? Assignment 3 You will be divided into four groups. And each group will work as a team and design a study about the prognosis of subclinical hyperthyroidism. We’ll have two groups presenting their designs and the two groups criticizing their work. Before you design the study, you can search the literatures to get some ideas about subclinical hyperthyroidism. The study design has not to be perfect, just try to consider the principles questions in prognosis. Each team needs to bring a computer to the classroom. During class, you’ll have some time to discuss your study, but it’s better to have an outline of your study design before you go to the class. And figure out who will present the study before class. Consider the following questions: 1 What are the potential prognostic factors for subclinical hyperthyroidism? 2 What specific prognostic factor you want to study? What study design you want to choose? Explain it. 3 Who will be your study population? a) Your inclusion criteria and exclusion criteria. b) How do you plan to select them? Hospital based or primary based? 4 What is your exposure ( definition)? 5 What outcomes do you want to measure? How do you plan to get them and have them ascertained? 6 How long is the follow-up period? What will you do to prevent loss to follow up? 7 What association measure do you plan to use? OR, RR, HR, Kaplan-Meier curve? 8 What potential confounders do you want to adjust? 第 80 页
The Medical Literature Users' Guides to the Medical Literature V. How to Use an Article About Prognosis Andreas Laupacis, MD, MSc: George Wells, MSc, PhD; W. Scott Richardson, MD: Peter Tugwell, MD, MSc for the Evidence-Based Medicine Working Group CLINICAL SCENARIO the dementia. You indicated that you nying the disease in question). They can pa You are about to see a 76-year-old would discuss this with him at the sec- predict any outcome, whether good (eg, retired schoolteacher for the second ond visit once the results of all the tests cure or survival) or bad (eg, death or To stud time. You first saw her in the clinic a are available complication). Prognostic factors need month ago because of cognitive prob- seArCh not necessarily cause the outcomes, just iduals wh eluded a Standardized Mini-Mental State Hoping to provide the son with the to predict their development. In the li- ontrol Examination,'on which she scored 18 his mother's prognosis, after the initial distinguished from"risk factors,"those thenumbe out of a possible 30 points, and a physi al examination that was normalinclud-. visit you searched the medical library,s patient characteristies associated with i ith a par ng no focal neurological signs. You ar- MEDLINE CD-ROM system via the. the development of the disease in the ranged investigations for the treatable: hospitals network on the clinic com- first place. For example, smoking is an more and you thus feel she has probable alz- ease "which yielded 3687 articles from ment of lung cancer, but is not as im he poter portant a prognostic factor as tumo The patient has lived with her son nosis, "which yielded 28004 articles;; stage in someone who has lung cancer /ses and heimer disease. nificant problems with her memory found several articles of potential inter- tic factors. Therefore, the best study de: relatives c about 3 years ago. However, she has est, including one that seemed precisely sign to identify the presence of and de quarts), im noid during the last year. She has re- Alzheimer-Type Dementia "by Walsh a prognostic factor is a cohort study. As sadie A fused to allow him to look after her fi..and colleagues. 2 nancial affairs, despite the fact that she series, investigators conducting cohort shut owns three pieces of property and isn't INTRODUCTION study follow one or more groups( cohorts able to manage them herself. Her son In this article we will suggest a frame- of individuals who have not yet suffered ase-cont hether she is likely to die soon' from sess articles that deal with prognosis, berofoutcome events over time. Anidea b prate whe using the article on patients with de- cohort study consists of a well-defined equired dr mentia as an example. We will follow sample of individuals representative Department of Clinical Fni Axiology the usual format of this series and dis- the population of interest and uses oP-.ARE THE F cuss how to determine whether the re- jective outcome criteria (Dr Laupacis): the Departments of Medicine and Epi- sults are valid, how to interpret the re- conducted in Framingham, Mass, in which THE ST semiology and Community Medicine, University of Ot- sults, and whether the information will investigators have followed a cohort ry G 5209individuals since 1948, has provided Was The (NY)School of Medicine and aprognosis'refers to the possible out. clinicians with a great deal of useful ir I Nell-Defir A complete list of members(with afflictions) of the comes of a disease and the frequency formation about the prognostic impor similar Po the first article of this series (AMAroup 800293. with which they can be expected to oc- tance of many determinants of can article: Gordon H. Guyat ( chair MD. MSc: George tia). Sometimes the characteristics of a ized trials include careful documentation /ed. The Gerstein, MD MSc: Brian. Haynes, MD. MSc, PhD: particular patient can be used to more of inclusion criteria and strict protocols and whe ir 3. MPH: Mitchell Levine, MD). MSc accurately predict that patient's even- for follow-up, patients in such trials form pheunderly Jim Nishikawa, MD: David. Sacket, MD MS: Patrick tual outcome(eg, a patient with demen- cohorts that can also generate informs mould desc HUrLe . sc: stephane sauve, MD, sc: virginia worse prognosis than someone without However, the patients entered into the David Naylor, D, Dp il: Andrew behavioral problems). These character- trial are often not representative of the Azh disorde elected th∈ eral b types, such as demographic(eg, age), morbid (eg, other conditions accompa-.JAMA 234JAMA,J20,1994vo272.No.3 Users' Guides to Medical Literature-Laupacis e
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Guides for an Articie About Prognosis from primary to tertiary centers raises long period, investigators must follow re the results of the study valid usual cases, thus increasing the likeli. patients for long enough to detect the Was there a representative and well-defined hood of adverse or nonfavorable out- currence in some women with early Was follow-up sufficiently long and complete? filter bias, "the likelihood of a subse- ter initial diagnosis and treatment. Pa- quent nonfebrile seizure in children with tients in the dementia study were en- their first febrile seizure was much lower rolled between 1980 and 1982 and fol- Was there adjustment for important prognostic in community-based populations than in lowed until 1988 or their death. Thus What are the results? those drawn from hospitals. the follow-up was quite long, and 61%of The second issue concerns whether the cohort died during this time the study patients are all at a similar, Ideally, investigators will succeed in the results help me in caring for my pa- well-defined point in the course of their following all patients(as they did in the disease. Authors should provide a clear. dementia study) but this is often not the to my own? the results lead directly to selecting or avoid- description of the stage of disease at case. Patients are not usually unavail- Are the results useful for reassuring or counseling instance, since the duration of illness is reasons. Patients may fail to return be- ey can often associated with outcome, the in- cause they have suffered exactly those vestigators should report the duration. events in which the investigators are ath or To study prognostic factors, investi- ofillness for the sample patients Within interested (eg, they died or have been ators can also collect"cases"of indi- reason, all or most of the study patients institutionalized). Conversely, patients es, just iduals who have already suffered the should be at a similar point, such as who feel entirely healthy may also be enough outcome event and compare them with survivors of a first myocardial infarc-. less likely to return for evaluation be- the lit ntrols” who have not. In these“case usually ontrol"studies the investigators count lung cancer. However, the similar point greater the number of patients unavail- those the number of individuals in each group:on. in the course of disease need not be early able for follow-up, the less accurate the 计 I a particular prognostic factor(eg estimate regarding the risk of the ad in the were the patients with dementia who Walsh and colleagues2studied 126- verse outcome. ig is an, died more likely to have had behavioral patients with Alzheimers disease who Under what circumstances does un- °如 the and controls, as well as the ret- twee9 diagnosis was you consider the relation between the velop- I problems than those who did not die?). were consecutively referred to a mul- availability for follow-up compromise the thia to prognostic factors (which often depends ing of an internist, psychiatrist, psycholog able and the proportion of patients wh orognos. on the memory of the patients or their gist, neurologist or neuropathologist, and have suffered the adverse outcome of tudy de- relatives or the accuracy of medical research nurse using the conventional interest. The larger the number of pa- and de. charts), limits the strength of inference Diagnostic and Statistical Manual of tients whose fate is unknown to ed with clinicians can draw from case-control. Mental Disorders, Fourth Revision cri- the number who have suffered an event teria for, dementia. The tests used to the greater the threat to the studys cudy, As I studies. Also, case-control studies can- exclude other causes of dementia were validity. Forinstance, letus assume that not provide information about the ab- a cohort solute risk of an event, but only about not described. However, given the mul- 30% of a particularly high-risk group (cohorts) I the relative risk (RR). Nevertheless, tidisciplinary nature and expertise of. (such as elderly diabetics)have suffered se-control studies can provide useful. the group, it seems reasonable to as-. an adverse outcome (such as cardiovas- Anidea f priate when the outcome is rare or the done to exclude disorders such as hy-. up. If 5% of the patients have been lost, defined i required duration of follow-up is long. pothyroidism, depression and space-oe. the true rate of patients whe khad died uses RE THE RESULTS fused with Alzheimers diseas so, the clinical implications would not ort stud T OF THE STUDY VALID? Walsh and colleagues reported sur- change, and the unavailability for follow vival from two different points in time: up doesn't threaten the validity of the (1)referral to the clinic and(2)the point study. However, in a much lower-risk provided Was There a Representative and at which symptoms of memory loss were patient sample(otherwisehealthy useful in Well-Defined Sample of Patients at a first noticed. The former is a more cer- middle-aged men, for instance)the ob- ic impor-I imilar Point in the Course of the Dis- tain point in time, but suffers from the served event rate may be 1%. In this of cardio ease?-This guide addresses two related disadvantage that patients cometo medi- case, if one assumed that all 5% of the mentation ined the individuals in the study are, progression of their disease. The latter died, the event rate of 6% would have protocols and whether they are representative of provides a more uniform starting point, very different implications. If the num rials form I the underlying population. The authors but is potentially imprecise because de- ber of patients unavailable for follow-up e informs should describe and specify their crite- entia develops insidiously and the time potentially jeopardizes the study,'s va establishing that the patient has of onset is identified retrospectively. lidity, you should look for the rea ad into the i the disorder of interest (in this case, Survival after presentation to clinic is for patients being unavailable, and com- tive of th azheimer-type dementia) and how they probably more relevant for your pa- pare the important demographic and lected their patient sample cteristic of the patic Was Follow-up Sufficiently Long who were unavailable with the patients by of the patients can distort the re- and Complete -since the presence of whom follow-up was complete. To the e Sections: a)ts of a study. For example the se-. a prognostic factor often precedes the extent that the reasons for disappear- ice of referrals that leads patients development of an outcome event by a ance are unrelated to outcome and the aupacs'eta AMA, Juth201940272.No.3 Users'Guides to Medical Literature- - Laupacis et al 235
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