megan von isenburg may 5, 2017 - ohsla - home · ebp the basics: study design and randomized...

Megan von Isenburg

May 5, 2017

EBP the Basics: Study Design and

Randomized Controlled Trials. 2017 2

EBM Basics:

- What?

- Why?

Study Design

- Hierarchy

- Searching

Randomized

Controlled Trials

- Randomization

- Critical appraisal

- Math

Image from Pexels

Study Designs

3


Randomized Controlled Trials. 2017



Shared Decision

Making

EBP the Basics: Study Design and Randomized Controlled Trials. 2017 5

Study

Design

1. Describe the studies used in

clinical

medicine

2. Identify the strengths /

weaknesses

3. Identify search

strategies in

PubMed

4. Identify study designs

from article

abstracts

Cookie-cutter medicine?

Following guidelines?

A bunch of algorithms in an EHR?



7

Assess

Ask

AcquireAppraise

Apply



P

I

C

O

Patient Problem, Population

Intervention, prognostic factor

Comparison

Outcome



Background◦ General knowledge

◦ What are the clinical manifestations of…?

Foreground◦ Seek specific knowledge to inform clinical

decisions

◦ In pediatric patients with rhinitis, are intranasal steroids more effective than antihistamines?





The better the

evidence the

more confidence

in the decision

Patient

values and

preferences

matter

Randomized Controlled

Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional

Case Reports/Case Series

EBP the Basics: Study Design and Randomized Controlled Trials. 201713



OBSERVATIONAL

RCT COHORT

CASE CONTROL

EXPERIMENTAL

ANALYTICALDescriptive

CROSS

SECTIONAL

QUALITATIVE

CASE

REPORTS

OBSERVATIONAL

RCT COHORT

CASE CONTROL

EXPERIMENTAL

ANALYTICAL

15EBP the Basics: Study Design and Randomized Controlled Trials. 2017

Is this EXPOSURE

(Intervention, prognostic factor, test, or study

factor)

Associated with this Disease or

OUTCOME



Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional



Starts with patients with an

OUTCOME

and looks back to an

EXPOSURE


EXPOSURENo

Cell phone usage

EXPOSURECell phone usage

OUTCOMENo Brain Tumors

21

OUTCOMEBrain

Tumors




Cheap

Quick

Rare outcomes

Ethical

Recall Bias

Confounders

Difficult to choose

control groups

a variable that is associated with both the

exposure and disease and could provide an

alternative explanation for why an exposure is

associated with a disease in a study.

http://theebmproject.wordpress.com/fundamentals/study_design/study-validity/



Confounder: obesity

Cases

Controls

TIME

Case-Control Study

Exposure

Absent

Exposure

Present

Measure HERE


Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional




Starts with patients with an

EXPOSURE and

follows them forward to

an OUTCOME


28

EXPOSURE

NO HRT

EXPOSURE

HRTOUTCOMENo Heart Disease

OUTCOMEHeart

Disease



Self Select


Ethical

Establish timing

Prospective

Show association

Time Consuming

Confounders


Confounder?

Outcome

Yes

Outcome

No

Exposure

Absent

TIME

Cohort Study

Exposure

Present

Measure HERE

Framingham Heart Study

NHANES Studies

Black Women’s Health Study

Nurses Health Study

Physician’s Health Study

Avon Longitudinal Study of Parents and Children (ALSPAC)


Cohort - Starts with patients

with an EXPOSURE and

follows them forward to

an OUTCOME;

Retrospective - All the data has

already been collected


EXPOSUREMI Admitted

weekday

EXPOSUREMI Admitted

weekend

2010-2013

Database

34

OUTCOMEIn-HospitalMortality

OUTCOMENo

In-HospitalMortality




Ethical

Establish timing

Data already

collected

Confounders

Data collected

before research

question

Retrospective Cohort Study

Outcome

Yes

Outcome

No

TIME

Exposure

Absent

Exposure

Present

Measure HERE


Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional




Start with patients who are

randomized to an EXPOSURE

and follows them forward to

an OUTCOME


40

EXPOSURE

NO HRT

EXPOSURE

HRTOUTCOMENo Heart Disease

OUTCOMEHeart

Disease



Randomized


Confounder?


Controls for bias

Balanced groups

Proves efficacy

Expensive

Ethical issues

Time consuming

TIME

Cure

No

Cure

Drug

Placebo

Randomized Controlled Trial

Measure HERE


Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional




Focuses on a clinical question

Conducts a thorough literature search

Validates credibility of the studies

Summarizes the data


AUTHOR'S CONCLUSIONS:

This systematic review,

incorporating the latest available

trial data, shows that hormone

therapy does not significantly

change the risk of all-cause

morality, CHD death or non-fatal

AMI but increases the risk of

stroke in postmenopausal

women.

46



47




Summarizes

studies

Validates smaller

studies

Generalizability

Saves time

Time Consuming

Publication bias

Heterogeneity

Case Control

Retrospective Cohort

Cohort





Descriptive

CROSS

SECTIONAL

QUALITATIVE

CASE

REPORTS


Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional




A report of a single unique or

unusual case or a number of

similar cases


53

ExposureLavender

OUTCOMEEnlarged Breasts





20172010 2019

EXPOSURE

OUTCOME


Brings to attention

unusual case

Start of research

Observation

No control

No association

No comparison


Trials

Cohort Study

Case Control Study

Meta -analysis

Systematic reviews

Cross Sectional




Both EXPOSURE and

OUTCOME are measured

simultaneously in a given

population


58

EXPOSURENew Test

AndGold Standard

Test

OUTCOMESensitivity/

Specificity of New Test




Shows accuracy

of new test

Calculate

likelihood ratios

Expensive

Ethical issues

60

OUTCOMEDoctor’s visit

EXPOSUREApple a day





20172010 2019

EXPOSURE

OUTCOME


Cheap

Easy

Ethical

Recall Bias

Confounders

Addresses questions related to the

human response to health issues.

Describes, explores and explains

human behavior.


Qualitative study

64



Qualitative study

Based mainly on their

family history and

lifestyle, women do

not generally

consider themselves

to be at personal risk of heart disease.

Ballard K. Understanding risk: women's perceived risk of menopause-

related disease and the value they place on preventive hormone

replacement therapy. Fam Pract. 2002 Dec;19(6):591-5. PubMed

PMID: 12429660.

65




Documents the

human experience

Motivations

Explains behavior

Poorly understood

Lack of objectivity

Lack of

Generalizability



Why is this important?



The better the

evidence the

more confidence

in the decision

Patient

values and

preferences

matter

P

I

C

O

T

T

Patient Problem, Population

Intervention, prognostic factor

Comparison

Outcome

Type of Question

Type of Study



Type of

Question

Type of

Study


Type of questions:

Therapy determine the effect of an

assigned intervention

Does this treatment work?

Study

Design:

Systematic Review/Meta-Analysis


Cohort Study


Type of questions:

Diagnosis Determine the ability of a test

to differentiate between those

with and without a target

condition

Is one test as good or better

than another test?

Study

Design:

Cross Sectional

Prospective comparison

Sensitivity and Specificity


Type of questions:

Prognosis Determine a patient’s likely

clinical course over time due to

factors other than interventions

What will happen to these

patients over time?

Study

Design:

Cohort Study


Type of questions:

Harm Determine the effects of

potentially harmful agents

Is this agent harmful?

Study

Design:

Cohort Study

Case-Control Study

*Randomized Controlled Trial


La

nce

t 2

00

2; 3

59

:57

-61


Know your chances. Steven

Woloshin et al. University of

California Press, 2008

79



ExerciseBuild-a-Study

Who is your population and how would you

select them?

Who is your comparison

group and how would you

select them?

What would you assess? What is the direction of

inquiry?

What are the Benefits and Problems?



Study

Design


clinical

medicine


weaknesses

3. Identify search

strategies in

PubMed


from article

abstracts

Publication Type

MeSH

◦ Case-Control Studies

◦ Cohort Studies

◦ Sensitivity and Specificity

◦ Qualitative Research

Clinical Queries


87



90



Cross sectional

Prospective blind comparison

Sensitivity and Specificity[MeSH]

Best way to search:

Specificity[tiab] OR Sensitivity and Specificity[MeSH]


Therapy

Diagnosis

Harm/Etiology

Prognosis



Can a Mediterranean-style diet reduce CV risk?

Your pediatric patient has abdominal pain. Should you use US or CT to rule out appendicitis?

Your new house is near power lines. Are you going to get leukemia?

Your patient suffered a TBI during a motorcycle crash and is in in a coma. When will he make a full recovery?

You know much has been written about ICDs for Afib and want to find something that synthesizes the evidence for you.


Study

Design


clinical

medicine

2. Identify the strengths/

weaknesses

3. Identify search

strategies in

PubMed


from article

abstracts

NAME THAT STUDY

1. Randomized Controlled Trial

2. Cohort Study

3. Case Control Study

4. Case Series

5. Systematic Review

6. Cross-Sectional Study


2. Cohort Study


4. Case Series



Persistent hiccups have been reported to occur occasionally during

rehabilitation hospitalizations. Hiccups can interfere with patient

participation and progress, and this can lengthen and complicate the

rehabilitation hospitalization. Chlorpromazine, the only Food and Drug

Administration-approved agent specifically indicated for hiccups, is often

chosen as a first-line treatment. However, chlorpromazine does not always

provide favorable results. The intent of this paper is to (1) review hiccups

and implications of persistent hiccups in the rehabilitation setting, (2)

provide additional evidence that chlorpromazine is often not the best

treatment choice for hiccups in rehabilitative patients, (3) report the

effectiveness and favorable tolerability of modest doses of gabapentin in a

small ________ of three patients, and (4) review potentially effective

treatment approaches for hiccups.


2. Cohort Study


4. Case Series





10

7

Study Design

should be part of

EBM search

strategy

Level of

evidence

matters

Study design

should

match

question

108




9

Study

Design


clinical

medicine


weaknesses

3. Identify search

strategies in

PubMed


from article

abstracts

Megan von Isenburg

[email protected]