GIẢI QUYẾT CÁC VẤN ĐỀ LÂM SÀNG.CƠ SỞ TỪ Y HỌC CHỨNG CỨ. GS.TS. BS. LÊ HOÀNG NINH

PowerPoint Presentation Gi i quy t các v n lâm sàng ả ế ấ đề C s t y h c ch ng cơ ở ừ ọ ứ ứ Gi NG VIÊN Ả GS TS BS LÊ HOÀNG NINH N i dung bài h c ộ ọ • Mục tiêu • Các kỹ năng cần của y học chứng cứ tro[.]

Gi i quy t các v n ả ế ấ đề lâm sàng:

C s t y h c ch ng c ơ ở ừ ọ ứ ứ

– Kỹ năng tìm kiếm các chứng cứ hiện có trên y văn

– Kỹ năng đánh giá các chứng cứ trên y văn

– Kỹ năng ứng dụng chứng cứ trên bệnh nhân của thầy thuốc

M c Tiêu ụ

• Định nghĩa y học chứng cứ (EBM)

• Tại sao thầy thuốc phải dùng y học chứng cứ

– Compare with expert-based medicine

– How are we misled by:

Y h c ch ng c là gì? ọ ứ ứ

“ sử dụng chứng cứ tốt nhất hiện có vào thực hành chăm sóc bệnh nhân”

Cái gì là quan tr ng khi ọ đọ c y v n ă

Cái cần có ở y văn là

1 Các kết quả có liên quan tới bệnh nhân của bạn

2 Trả lời được câu hỏi về chăm sóc bệnh nhân mà bạn đang gặp

khó khăn

3 Có thể làm bạn thay đổi thực hành chăm sóc bệnh nhân của

bạn

4 Là chủ đề mà bạn đang quan tâm theo dõi

5 Là cái mà bạn cần biết rõ hơn, chi tiết hơn, cụ thể hơn

6 Bạn cần về POEM or DOE

• Patient-oriented evidence ( POEM: bằng chứng hướng tới

bệnh nhân ) that matters vs disease-oriented evidence ( DOE : bằng chứng hướng tới bệnh )

Giá tr c a vi c h c EBM: ị ủ ệ ọ

( m t th nghi m ng n h n) ộ ử ệ ắ ạ

• Một thử nghiệm có nhóm chứng về giảng dạy đánh giá y

văn được thực hiện trên sinh viên y khoa

khóa huấn luyện lâm sàng về:

– Đánh giá các thử nghiệm lâm sàng

– Đánh giá các bài báo về test chẩn đoán và điều trị

qua các khóa huấn luyện kể trên

Bennett et al JAMA 1987;257:2451-2454.

Giá tr vi c h c EBM: ị ệ ọ

( m t th nghi m ng n h n tt) ộ ử ệ ắ ạ

• Sinh viên nhóm thử nghiệm có quyết định chẩn đoán

và điều trị đúng tốt hơn và họ có thể lập luận, bình luận trước khi ra các quyết định của họ

• Những sinh viên trong nhóm chứng thường ra các

quyết định không đúng trong chẩn đoán và điều trị.

• Sinh viên trong nhóm chứng thường dễ chấp nhận

những đề nghị từ những nhân vật có thẩm quyền.

Bennett et al JAMA 1987;257:2451-2454.

• no known infectious exposure/

suspicious ingestions, or recent travel

H ướ ng d n truy n th ng trong th c hành ẫ ề ố ự

y khoa

• Pathophysiology and pharmacology

– Foundation of medical practice

– Do what “makes sense”

• Expert opinion

– In training: learning at the bedside from the master clinician – In practice: lectures and seminars with thought leaders

• Clinical experience

– Successes, outcomes, and adverse events

in our own practice

Chứng

cứ hiện

có tốt nhất

Kinh

nghiệm

lâm sàng

Hiện trạng và Bối cảnh bệnh nhân

i U TR VÀ CH N OÁN Đ Ề Ị Ẩ Đ

• Không nôn mửa, tiêu chảy, không có nhu động ruột

• Không rõ tiếp xúc với nguồn nhiễm trùng, suspicious

ingestions, or recent travel

no heptomegaly nor splenomegaly (enlarged liver or spleen) She has no rebound pain or involuntary

chu n 5 “A” ẩ

1 Ask the right question

2 Acquire the evidence

3 Appraise the evidence

4 Apply the evidence

5 Assess its impact

• Case discussion: 27 year old woman with right lower

quadrant (RLQ) abdominal pain

• Background information available from

textbooks-– What typically presents as RLQ pain

– What is the clinical course of the different diagnoses

– Specifically, what is typical presentation of appendicitis

• Foreground information

– How good is a CT scan for appendicitis?

t Câu H i Lâm Sàng

Câu H i Lâm Sàng ỏ

• Câu hỏi lý tưởng:

– Focused enough to be answerable

– Pertinent to clinical scenario

Examples of tough questions

• Should I screen men for prostate cancer?

• Who is a good candidate for hormone replacement therapy?

• Are angiotensin receptor blockers now first-line for hypertension?

Examples of better questions

• Would a PSA test reduce mortality in a 65 year-old

asymptomatic man?

• What is the reduction in fracture risk associated

with hormone replacement therapy?

• Is losartan more effective than atenolol at

preventing cardiovascular events in middle-aged hypertensive diabetic women?

PICOS

PICOS for confirmatory diagnosis of appendicitis

P: 27 year old woman with symptoms suggestive of

H qu quan tr ng ệ ả ọ

• Hệ quả hướng tới bệnh nhân:

outcomes patients actually care about

– Death (overall or disease-specific)

– Heart attacks, strokes, amputations, bed sores, broken hips,

renal failure, etc.

– Ability to perform activities of daily living

Versus

• Hệ quả hướng tới bệnh:

– Biochemical, physiologic, pharmacologic, or laboratory measures

Comparing DOE and POE

Shaughnessy AF, Slawson DC Getting the Most from Review Articles: A Guide for

Readers and Writers American Family Physician 1997 (May 1);55:2155-60

Example Disease-Oriented Evidence

Patient-Oriented Evidence that Matters Comment

Antiarrhythmic

Therapy Drug X  PVCs on ECG Drug X increases mortality POE contradicts DOE

Type 2 Diabetes Aggressive Tx

with insulin or oral agents can keep BS low

Aggressive Tx does not reduce mortality or

prevent most complications

POE contradicts standard teaching

Prostate

Screening PSA screening detects prostate

cancer early

Does PSA screening  mortality?

DOE exists, but POE is unknown

Background versus foreground

information

• Case discussion: 27 year old woman with right lower

quadrant (RLQ) abdominal pain

• Background information available from

textbooks-– What typically presents as RLQ pain

– What is the clinical course of the different diagnoses

– Specifically, what is typical presentation of appendicitis

• Foreground information

– How good is a CT scan for appendicitis?

Steps of EBM-5 A’s

“Finding Evidence”: Sources (I)

• Primary research database (articles)

– PubMed (aka MEDLINE), Pyschlit, CCTR

• Secondary research databases (synthesis)

– Cochrane Library, Clinical Evidence, InfoPOEMS, UpToDate

• Tertiary resources (meta search engines, databases of databases)

– TRIP+ (Translating Research Into Practice), PrimeEvidence

“Finding Evidence”: Sources

• PubMed

– 16 million peer reviewed biomedical articles indexed (note can use PubMed

limits to search on particular populations, study types, etc.)

– ~3000 regularly updated entries, Patient Oriented Evidence the Matters

(POEM), 100+ journals monitored

• UpToDate

– 70,000 pages, evidence based clinical information resource, ~3000 authors,

350+ journals monitored, peer reviewed

• TRIP+

– Meta-search of 55 sites of evidence based information

“Finding Evidence”: Searching

1 Chuyển câu hỏi lâm sàng thành câu hỏi đúng dễ tìm y văn (e.g PICOS)

2 Chọn nguồn dữ liệu mà bạn muốn tìm (e.g PubMed)

3 Áp dụng bộ lọc để khu trú y văn cần tìm (e.g PubMed limits linked to PICOS

such as gender, age, study type limits)

4 Đánh giá kết quả (e.g using systematic review worksheet)

5 Xem xét xem liệu bạn có đủ thông tin để ra quyết định không

6 Nếu chưa đủ bạn phải đi lại các bước 1-3 cho đến khi bạn có được câu trả lời

hoặc quyết địnhlà không đủ chứng cứ hoặc có đủ chứng cứ để ra quyết định

ÁNH GIÁ CH NG C

Assess the Evidence

– Các Kết quả có ý nghĩa thống kê ?

• Kết quả áp dụng trên bệnh nhân được không?

– Does my patient resemble those in the study?

– Were all outcomes relevant to my patient evaluated?

– Are there other factors (eg, cost, availability) that limit applicability to my

patient?

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago, IL:

American Medical Association; 2001

ánh giá ch ng c (t.t)

• Phân biệt nghiên cứu quan sát và thực nghiệm

observational and experimental studies

• Phân biệt 2 major study designs (randomized controlled

trial and cohort study) :

– How the study is designed

– Advantages and disadvantages of design

– How to assess validity

– How to assess results

– How to assess applicability

Nghiên c u th c nghi m ứ ự ệ

• In experimental studies, the investigator controls subjects’

exposure to intervention

– Example: randomized controlled trial (RCT)

• In observational studies, investigator does not control the

exposure; it occurs naturally or is initiated by patients or their physicians

– Examples: cohort study, case-control study

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical

Practice Chicago, IL: American Medical Association; 2001.

RCTs: ích l i ợ

• Treatment and control groups are likely to have similar distribution

of known and unknown prognostic factors (potential confounders)

• Outcomes are determined prospectively in a standardized,

systematic fashion

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based

Clinical Practice Chicago, IL: American Medical Association; 2001.

RCTs: Disadvantages

• Costly to perform

• Size limitations make detection of rare events difficult (eg, adverse

medication effects)

• Eligibility restrictions may reduce applicability to real patients

• Cannot be ethically performed if exposure is expected to cause harm

(eg, smoking)

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice

Chicago, IL: American Medical Association; 2001.

RCTs: Disadvantages

• Costly to perform

• Size limitations make detection of rare events difficult (eg, adverse

medication effects)

• Eligibility restrictions may reduce applicability to real patients

• Cannot be ethically performed if exposure is expected to cause

harm (eg, smoking)

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago, IL:

American Medical Association; 2001.

ánh giá giá tr các RCTs

• Was randomization concealed ?

• Were patients analyzed in groups to which they were

randomized?

• Were patients in treatment & control groups similar with

respect to prognostic factors?

• Were patients, clinicians, outcome assessors, and data analysts aware of allocation?

• Were groups treated equally ?

• Was follow-up complete ?

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago, IL: American Medical

Association; 2001.

ánh giá k t qu RCT

• Magnitude of result: How large was the treatment effect?

– Relative risk and odds ratio

– Absolute risk reduction and number needed to treat (NNT)

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago,

IL: American Medical Association; 2001.

Calculating the Risk Ratio and Number

120 have the outcome

– “Table 1” data (baseline characteristics)

• Were all clinically important outcomes considered?

• Are the likely treatment benefits worth the potential harm and costs?

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice

Chicago, IL: American Medical Association; 2001.

• Can be used to assess effects of harmful exposures (eg, smoking)

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical

Practice Chicago, IL: American Medical Association; 2001

H n ch nghiên c u oàn h ạ ế ứ đ ệ

• Costly to perform

• Size limitations make detecting rare events difficult

• Exposure and control groups are likely to differ in factors that may

affect outcomes

• Control of confounding through statistical analysis may be

inadequate

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical

Practice Chicago, IL: American Medical Association; 2001.

ánh giá giá tr nghiên c u oàn h

• Were the exposed and control groups similar in all known

determinants of outcome?

– Did the analysis adjust for potential differences?

• Were the outcomes measured in the same way in the groups being compared?

• Was follow-up sufficiently complete?

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice

Chicago, IL: American Medical Association; 2001.

ánh giá k t qu NC oàn H

• How strong is the association between exposure and

outcome?

– Risk ratio or odds ratio

– Absolute risk increase or number needed to harm (NNH)

• Statistical significance

– P value

– Confidence interval: How precise was estimate of risk?

• Clinical significance

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago, IL:

American Medical Association; 2001.

ánh giá tính ng d ng Cohort

Study

• Were the study patients similar to

the patient under consideration in

my practice?

• Should I attempt to stop the exposure?

Guyatt et al Users' Guides A Manual for Evidence-Based Clinical Practice Chicago, IL: American Medical Association; 2001 to the Medical Literature:.

Nghiên c u b nh-ch ng ứ ệ ứ

• In contrast to RCTs and cohort studies, participants are selected

based on the presence of the outcome rather than the exposure

• Exposure status is determined retrospectively

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical

Practice Chicago, IL: American Medical Association; 2001.

Case-Control Studies: Design

(diseased ) Controls (nondiseased)

Exposed Not Exposed

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice Chicago, IL: American Medical Association; 2001.

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical

Practice Chicago, IL: American Medical Association; 2001.

H n ch Case-Control Studies ạ ế

• Retrospective assessment of exposure may be

inadequate ( recall bias )

• Can be performed only after outcomes have occurred

(ie, after damage has already occurred)

• Selection of appropriate controls may be difficult

may be inadequate

Guyatt et al Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice

Chicago, IL: American Medical Association; 2001.

Các b ướ c EBM-5 A’s

Applying EBM

Clinical

Expertise

Patient Values and

Preferences

Quality

Best Available Evidence

Xem xét k t qu nghiên c u i u tr ế ả ứ đ ề ị

VALIDITY

• Clearly focused question?

• Randomization

• Blinding- subjects, providers, investigators

• Groups similar at start and treated the same throughout?

• Followed in randomized groups and accounted for at end? (intention to treat)

• Enough subjects to minimize chance differences?

REUSLTS AND PRECISION

1 What are results? How presented?

2 Certainty & precision? (95% CI’s)

APPLICABILITY

1 Can the results be applied to my patient?

2 All important outcomes addressed?

3 Should there by change in policy?

“Therapy”: Intention to treat

• Subjects are analyzed in the groups they were randomized to.

– Maintains randomization

– Better reflects real world outcomes

– Measures efficacy (“Will this work?”)

– Detects issues about intervention other than

effectiveness “In the best possible circumstances, do they work?”

“ i u tr ”: Di n Đ ề ị ễ đạ t các k t qu ế ả

Risk = outcome event rate

= number having event number receiving the intervention

Relative risk = risk in intervention group

(RR) risk in control group

Relative risk reduction (RRR) = 1 - RR

“ i u tr ”: Di n Đ ề ị ễ đạ t các k t qu ế ả

Absolute risk reduction (ARR)

= difference in risk ( control – intervention )

“Di n ễ đạ t các K t qu ế ả

Number-needed-to-treat (NNT) = 1/ARR

NNT: là số bệnh nhân cần được điều trị nhằm ngăn ngừa một biến cố, một hệ quả có thể xảy ra trong một thời khoảng nhất định nào đó