Course: Research in Biomedicine and Health IIISeminar 2: Asking a question

EBM steps◦Step 1: Formulating questions that can be

answered◦Step 2: Finding best evidence◦Step 3: Quick critical assessment of the

evidence◦Step 4: Applying evidence◦Step 5: Assessing effectiveness and

efficiency of the process

“PICOT” model:Patient (For which patient, population or problem you need information?)Intervention/indicator (What is the intervention you are studying?)Comparison/control (Which is the alternative treatment?)Outcome

(What is the effect of the intervention?)Type of study(Which is the optimal study design ?)

Who is treated?

What is given as a treatment?

What is the comparison?

What outcome is of interest to us?

How to ask a clinical question?

What is the study design?

Question type Ideal study design

Therapy RCT

Prevention RCT > Cohort> Case-control

Diagnosis Prospective, blind, randomized trial of comparison with golden standard

Prognosis Cohort> Case-control> Case series/ Case report

Cost and efficiency Economic analysis

Phenomenon Qualitative study

Be precise!

Kew words for database search

PPatient,

problem

Iintervention

CComparison

(not always)

OOutcome

TType of

study

Aim of steps 1. i 2. : find “pearls”

Examples of clinical questions

• What is causing migraine?• How often a 40 year-old women needs to go to

mammography?• What is the efficacy and safety of early and long-term

use of clopidogrel and aspirin compared to aspirin alone in patients with acute coronary syndrome without ST-segment increase?

• In patients with mechanical ventilation longer than 48 hours, is oral decontamination with chlorchexidine (CHX) or CHX + colistine useful in decreasing the risk of pneumonia related to ventilation?

Examples of clinical questions

Ethiology and risk factors

Ethiology and risk factorsWhat is causing the problem?

PrevalencePrevalenceHow common is the problem?

Has this patient a problem? DiagnosisDiagnosis

Who will have a problem? Prognosis and prediction

Prognosis and prediction

InterventionInterventionHow to treat a disease or

condition?

What is the problem? PhenomenonPhenomenon

Interventions cover a wide spectrum of activities - from medications and other clinical therapeutics to change in life habits (exercise, smoking cessation) and social activities (education programmes).

Interventions may include patient care for a single patient but also public health activities.

28 year-old man suffers from furunculosis in the last 8 months. These episodes are treated by drainage and 2 different atibiotics, but the disease relapses. The patient asks if the relapses can be prevented.

Patient with recurring furunculosis

Prophylactic antibiotics

No treatment

Decrease in relapse of furunculosis

Q: In patients with recurring furunculosis, can prophylactic antibiotic therapy in comparison to no treatment decrease the incidence of recurring episodes?

Reading a medical journal, you find an article about imiquimode cream for the treament of basal cell carcinoma. The notion of a cream as cancer therapy sounds surprising, so you wonder about its efficacy, especially in regard to long-term cure rate.

Patient with basal cell carcinoma

Imiquimode cream

Active placebo – standard/gold therapy

Increase in long-term cure rate with the cream

Q: In patients with basal cell carcinoma, can im iquimode cream , in comparison to standad surgical intervention, increase the long-term cure rate in these patients?

Questions about ethiology and risk factors are questions about what causes a disease or health condition.

Harmful outcomes of activities or exposures Common in public health:

◦ Can intake of certain food increase risk of cardiovascular disease?

◦ Can exposure to infrared waves increase risk of cancer?

Jane is expecting her first baby in two months. She read about the benefits and harms of injections of vitamin K to newborns. She is scared by the reports of increased risk of childhood leukemia in babies administered vit. K injections. She asks you if this is true and what the risk is for her baby.

Newborn

Vitamin K injection

No vitamin K injection

Childhood leukemia

Q: In newborns, does the administration of vit. K injection increase the risk of childhood leukemia?

Questions about how many people have a diseases or health condition.

Examples:◦ What is the prevalence of hearing problems in

newborns?◦ What is the prevalence of Alzheimer’s disease in

the population older than 70?

Maria is a 6-month baby coming to her regular check up. She was born prematurely, at the gestational age of 35 months. You want to warn the parents about the odds that Maria may have hearing problems.

Infant

Premature birth

Term birth

Deafness

Q: In preterm infants, in comparison to term babies, what is the prevalence of deafness?

Questions about:◦ How accurate are diagnostic tests in different patient groups. ◦ How accurate are diagnostic tests in comparison to other

tests.

Clara is pregnant for the second time. She had her first baby when she was 30 and had amniocentesis to exclude Down’s syndrome. The test was negative, but she was not satisfied because she got results in the 18th pregnancy week. She is now 35 and asks if there is a test with a quicker answer. Your hospital has biochemical test of serum markers and ultrasound of nuchal folds in the first trimester, but you want the check if the test is sensitive and specific enough in comparison to amniocentesis.

Pregnant women

Serum markers biochemistry +US of nuchal folds

Amniocentesis

Correct diagnosis (specificity and sensitivity) of Down’s syndrome

Q: In pregnant women, is nuchal fold US + serum markers test equaly correct as amniocentesis in diagnosing Down’s syndrome?

What are the odds for an outcome for a population with certain characteristics (risk factors)?

◦ What are the odds that a man who feels atypical chest pain develops heart failure?

◦ What is predicted mortality and morbidity for a person who is diagnosed with colon cancer?

Clonic seizures in childhood are common and disturbing for parents, but the decision to start prophylactic therapy after the first attack is difficult. To help parents make a decision, you have to explain them the risk of new attacks after the first clonic seizure of undetermined cause.

Children

A clonic attack of undetermined cause

No attack

Future attacks

Q: In children with a single clonic attack of undetermined origin, in comparison to children without attacks, what is the risk of future clonic seizures?

• For each type of clinical question there are study designs that provide best evidence for the question.

• These are always study designs that have a maximum decrease in bias .

Question type Ideal study design

Therapy RCT

Prevention RCT > Cohort> Case-control

Diagnosis Prospective, blind, randomized trial of comparison with golden standard

Prognosis Cohort> Case-control> Case series/ Case report

Cost and efficiency Economic analysis

Phenomenon Qualitative study

Observational

Design

Experimental

No control Cohort

Case-control

Non-randomized control

Randomized control

Open

Single blind

Doubleblind

Increasing validity of evidence for conclusions on cause and consequence

Examples of disbalance between surogate and relevant outcomes:

Disease or condition Surogate outcome Relevant outcome

Lidocaine for arrythmia after AMI

Decreases arrythmia Increases mortality

Vitamin E for heart disease

Decreases the level of free radicals

Do not decrease mortality

Clofibrate for hyperlipidemia

Decreases blood lipid levels

Do not decrease mortality

Sodium floride for bone fracture prevention

Increases bone densitiy Do not decrease fracture rate

Hormone replacement therapy

Decreases LDL, increasese HDL

Do not decrease mortality, can increase incidence of cardiovascular events in women over 60