528 Evidence-Based Medicine (EBM) and Intro to Epidemiology

______ disease is most frequently studied in affluent countries

Chronic

Research tends to favor ____ drugs

NEW

- where the money is

- the QS being asked

- what gets published

Research agenda is set by _________ and ______ funding

federal funding - fairly small percentage

private sector pharmaceutical R&D companies

Why is Chronic disease is most frequently studied in affluent countries?

Biggest profit potential

• Incidence and prevalence

• Need to take medications indefinitely

• How many different statins are needed?

• How many different ACE inhibitors are needed?

Selection of study subjects for clinical trials who are:

• More likely to respond favorably to treatment

• Less likely to have side effects

• Do not have other diseases

Selection of study subjects for clinical trials: Exclude subjects who/who are

• Older

• Do not speak English

• More likely to be lost to follow-up

• Taking other chronic medications

• Have more conditions than the chronic disease of interest

• At high risk for outcome

Predictor variables

the previous exposure the subject has that can affect the outcome (ex:diabetes)

Outcome variables

dependent variables

outcome of the study

Quality elements of how a study is designed and conducted

Do investigators know who is receiving drug or placebo?

Do investigators control who receives which treatment?

Do investigators measure the effects the same way in all subjects?

What are the rules for stopping a study?

• How many comparisons are being made?

• Fraud

Type of outcome measured

• Clinical measure - MI

• Surrogate measure - Cholesterol measures

• Efficacy versus effectiveness

EVIDENCE ALONE IS NOT ENOUGH TO MAKE A CLINICAL DECISION: CLINICIANS MUST BALANCE THE

Benefits, costs, and nuisance of treatment/care options: balancing patient preferences and values with clinical decisions

Evidence-Based Medicine Philosophy is Based on Three Key Principles:

• Awareness of best clinical evidence

• Hierarchy of evidence exists, and it is used to guide clinical decision-making

• Evidence alone is not enough to make a clinical decision

Evidence alone is not enough to make a clinical decision

• Clinicians must balance risks, benefits, costs and the nuisance of treatment/care options

• Clinicians must factor in patient preferences and values to make clinical decisions

Hierarchy of Medical Evidence for Prevention and Treatment Decisions or Therapeutic Treatment Decisions:

framing the clinical question invoves

patients

expourse

outcome

PICO

Clinical questions can be separated into _________ and _________

background questions and foreground questions

background questions

Typically answered using available tertiary literature (for example, textbooks) and are used to gain foundational knowledge

• Sometimes secondary literature is used

• Typically asked bya novice health professional

Foreground questions

usually require primary literature and are used for problem-solving

• Occasionally, secondary literature is used

• Typically asked by experienced health professionals

must be framed in a way they can beanswered given the large amount of existing information

PICO- P=

Patients or Population

• Which patients are relevant to the question?

PICO: I

Intervention (s) or Exposure(s)

• Which medications, risks, interventions, time period is/are of interest?

• What management or treatment strategies are of interest?

PICO: C

Comparator

• What are we comparing the medication, risk intervention or strategy of interest to?

PICO: O

Outcome

• What happens to the patient or population because of the exposure or intervention

5 Types of Clinical Questions

1) Therapy

2) Harm

3) Differential diagnosis

4) Diagnosis

5_ Prognosis

Therapy questions

used to determine the effect of exposures or interventions on patient outcomes

EX: Do patients with IBS experience fewer symptoms with medications than with dietary changes alone?

Harm questions

used to determine harmful effects of exposures or interventions on patient outcomes

• Can use these in conjunction with studies of therapy questions - what are the adverse effects of interventions

EX: Do CHF patients treated with amiodarone experience harmful side effects?

Differential diagnosis questions

are used to determine the frequency of various medical disorders in patients with particular clinical presentations

EX: In patients presenting with fever and chills, is it more likely they have influenza or malaria?

Diagnosis questions

are used to determine the ability of a test to separate or differentiate between individuals with and individuals without a disease or condition

EX: What is the sensitivity of a pregnancy test in determining women who are really pregnant?

Prognosis questions

used to assess or approximate a patient's future course

EX: How long will patients with hyperlipidemia who have already experienced one MI and are now being managed with statin therapy survive before a second MI?

Epidemic VS pandemic

epidemic is in a region or area

pandemic is a large area, often globally

Epidemiology

is the study of frequency and distribution of disease occurrence, as well as factors associated with disease occurrence or disease distribution in populations

concerned with distribution and determinants of health anddiseases, morbidity, injuries, disability, and mortality in populations*

Epidemiologic studies are applied to ....

control health problems in populations

Objectives of Epidemiology

1. . Identify etiology of disease and relevant risk factors

2. Determine disease burden in a community or communities

3. Study course or natural history of disease and its prognosis

4. Evaluate existing and emerging preventive routes and therapies, as wellas health care delivery methods

5. Provide supporting knowledge to develop public policy that relates to providing disease prevention and health promotion. Environmental.

Genetics

Other concerns affecting health

Determinants

factors or events that can cause a change in health/health status

Determinants Examples

• Infectious agents

• Chemical agents

• Environmental agents

• Personal habits or customs

Social determinants of health

Social determinants of health

are the circumstances in which people are born, grow up,live, work, and age, as well as the systems put in place to deal with illness

Frequency of disease

occurrence, mortality, morbidity or other measures vary from one population to another population

Distribution

reflects how disease or other measures occur in different groups or populations of people

Epidemiology focuses on _______ RATHER than ______

disease and mortality in populations rather than individuals

morbidity vs mortality

Morbidity: illness

Mortality: death

morbidity rate

Number of illness occurrences or number of disease cases in a specific population in a given time period

Mortality rates

Number of deaths in an area per time period (often per year)or in a specific population per time period

epidemiologic description includes

variations by age, gender, time, geography,as well as other terms

Clinical description

signs and symptoms

EBM

evidence based medicine