Lecture 1. Epidemiology Introduction 16-
03-2020
Session I
“Epidemiology is the science that studies the occurrence of diseases in large populations of
people as a function of determinants”. Epidemiology is an essential science for the conduct
of ‘Evidence Based Medicine’.
What is wrong with this child? - diagnostics
Cause of the disease? - etiology
Future of this child? - prognosis
‘best’ treatment? - intervention/therapy
How to prevent? - intervention/prevention
Expensive to prevent? - efficiency/ economics
Research topics in epidemiology: etiology, diagnostics, prognostics and intervention.
Etiology/intervention Vs. Diagnosis/prognosis
Causal associations/studies predictive associations/studies
analytical studies descriptive studies
Case-control/RCT cohort design
Mostly 1 determinant more determinants
Confounding bias no confounding bias
Explanatory statistical model predictive statistical model
The cutter catastrophe
Cutter laboratories: famous, but chaotic. 1/3 lots were unsafe, and no documents were
reported, because this was not obligatory at that time. Eventually all cutter vaccines were
withdrawn from the market, but left with enormous damage…
- 220.000 people were infected with polio
- 70.000 cases of muscle weakness
- 164 cases of severe paralysis (75% permanent)
- 10 died due to polio
Nowadays vaccines are part of worldwide children vaccination program (DKTP Netherlands)
Typical research questions:
- What proportion of the population is using
drugs/vaccines?
- Which determinants predicts the use of drugs/vaccines?
- Do drugs/vaccines lead to a reduction in diseased
cases/mortality /increase in quality of life?
- What type of and how many side effects are caused by
drugs/vaccines?
,Drugs that have cause severe adverse reactions
Rofecoxib had a higher incidence
rate compared to naproxen.
However, when the
recommended dosage were taken
into account (new: <25 mg/day) it
has the same incidence rate
regarding cardiovascular disease. It
can be concluded: So It was not a feature of the drug, but it was a feature of the patient.
Patients brought too much rofecoxib.
4 main reasons for dangerous side effects and withdrawal
1. Clinical trials aren’t as big as you may think
2.‘Real world” use of a drug differs
3. Time plays a role
4.Off-label prescribing may bring up unexpected issues.
Also positive suspected effects are identified
New indications:
- Finasteride (benign prostatic hyperplasia) - hair growth
- Statins - sepsis, COPD exacerbations, infections?
- Sildefanil (Viagra- heart related chest pain) - erectile dysfunction
Protective effects:
- Acetylsalicylic acid - protection colorectal cancer?
- Bisphosphonates - protection breast cancer?
Example: ACE-inhibitor - reduction of sleep/anxiety problems?
Session II
In type 1:
Drug X is what we call the outcome of
our study question.
Patient Y is what we call the study
domain.
Age and sex are the determinants of
the outcome.
In type 2:
Drug X is the exposure/determinants
Disease Z is the study domain
Outcome Y is the outcome
,Another example: to what extent prevents polio vaccination the occurrence of polio in
children. Here the polio vaccination is the main determinant. Polio is the outcome and
children is the domain.
Types of epidemiological studies
- Experimental studies, in which I the
investigator get to determine in what you as
participant are going to get. That is what we
call clinical trials (RCTs few subjects). If
we talk about bigger communities
community intervention trials. Field trials
are even bigger (e.g. malaria trials). In
general, assigning people or things to group
and apply some treatment to one of the groups, while the other group does not
receive the treatment.
- Observational studies, where the investigator has no influence on whether you get
your vaccine or not. Thus, we measure or survey members of a sample without trying
to effect them.
Randomized Clinical Trials (RCTs) Observational (postmarketing surveillance (PMS)
limited number of patients large number of patients
Limited time unlimited time
Homogenous population drug-users in practice
Other variable excl. or controlled other influences (e.g. smoking, other drugs,
Nutrition.
Important clinical information that has to be obtained from PMS research:
- Usage and determinants in practice
- Effects in daily practice
- Adverse effects
- Drug interactions
- Usage of drugs for other indications (off-label)
- New applications
- Applied dosage and duration
- Usage/effect in children, elderly, pregnant woman
, - Effect on ‘hard’ endpoint (disease/mortality)
- Effect on population level (for example regarding the corona virus)
- Pharmaco-economics
- Cost
- Compliance
- Cost-effectiveness of interventions
Terminology of the word ‘effect’
- Efficacy: effect in clinical trials or laboratory studies
- Effectiveness: effect in daily practice
- Efficiency : costs in relation to effects
Post-marketing surveillance/phase IV research
- Definition: “monitoring all (anticipated and unanticipated) desirable and undesirable
(adverse)-effect of drugs to human health, after these drugs are released on the
market”.
- Goals is to obtain scientifically data on rational and safe use of drugs. It is obligatory
for pharmaceutical companies to have a ‘Risk Management Plan’ for all drugs that
are released on the market. In the RMP a company explains which studies are
performed to increase knowledge about the risks of drugs.
The institute of medicine has set up some guidelines to better monitoring and reporting on
the drug safety. They enforced the FDA/EMA to have authority on research from
pharmaceutical companies. They also have black triangle on newly approved drugs (these
needs to be studied more intensively). ‘Direct-to-consumer advertising’ prohibited in the
first 2 years after registration.
Who has interest in PMS?
- Patients: wants an effective and safe drug with reliable information.
- Physician/pharmacist: wants reliable and complete information to make a good
decision.
- Insurance company: importance of rational prescribing with regards to cost.
- Government: responsible for registration and population health.
- Industry: wants a good product.
Information sources for PMS (pharmaco-epidemiological research)
- Spontaneous reporting systems: e.g. LAREB
- Routine (administrative) databases: e.g. prescription databases
- Questionnaires/interviews/web-based
- Cohort/physical testing/lab data
03-2020
Session I
“Epidemiology is the science that studies the occurrence of diseases in large populations of
people as a function of determinants”. Epidemiology is an essential science for the conduct
of ‘Evidence Based Medicine’.
What is wrong with this child? - diagnostics
Cause of the disease? - etiology
Future of this child? - prognosis
‘best’ treatment? - intervention/therapy
How to prevent? - intervention/prevention
Expensive to prevent? - efficiency/ economics
Research topics in epidemiology: etiology, diagnostics, prognostics and intervention.
Etiology/intervention Vs. Diagnosis/prognosis
Causal associations/studies predictive associations/studies
analytical studies descriptive studies
Case-control/RCT cohort design
Mostly 1 determinant more determinants
Confounding bias no confounding bias
Explanatory statistical model predictive statistical model
The cutter catastrophe
Cutter laboratories: famous, but chaotic. 1/3 lots were unsafe, and no documents were
reported, because this was not obligatory at that time. Eventually all cutter vaccines were
withdrawn from the market, but left with enormous damage…
- 220.000 people were infected with polio
- 70.000 cases of muscle weakness
- 164 cases of severe paralysis (75% permanent)
- 10 died due to polio
Nowadays vaccines are part of worldwide children vaccination program (DKTP Netherlands)
Typical research questions:
- What proportion of the population is using
drugs/vaccines?
- Which determinants predicts the use of drugs/vaccines?
- Do drugs/vaccines lead to a reduction in diseased
cases/mortality /increase in quality of life?
- What type of and how many side effects are caused by
drugs/vaccines?
,Drugs that have cause severe adverse reactions
Rofecoxib had a higher incidence
rate compared to naproxen.
However, when the
recommended dosage were taken
into account (new: <25 mg/day) it
has the same incidence rate
regarding cardiovascular disease. It
can be concluded: So It was not a feature of the drug, but it was a feature of the patient.
Patients brought too much rofecoxib.
4 main reasons for dangerous side effects and withdrawal
1. Clinical trials aren’t as big as you may think
2.‘Real world” use of a drug differs
3. Time plays a role
4.Off-label prescribing may bring up unexpected issues.
Also positive suspected effects are identified
New indications:
- Finasteride (benign prostatic hyperplasia) - hair growth
- Statins - sepsis, COPD exacerbations, infections?
- Sildefanil (Viagra- heart related chest pain) - erectile dysfunction
Protective effects:
- Acetylsalicylic acid - protection colorectal cancer?
- Bisphosphonates - protection breast cancer?
Example: ACE-inhibitor - reduction of sleep/anxiety problems?
Session II
In type 1:
Drug X is what we call the outcome of
our study question.
Patient Y is what we call the study
domain.
Age and sex are the determinants of
the outcome.
In type 2:
Drug X is the exposure/determinants
Disease Z is the study domain
Outcome Y is the outcome
,Another example: to what extent prevents polio vaccination the occurrence of polio in
children. Here the polio vaccination is the main determinant. Polio is the outcome and
children is the domain.
Types of epidemiological studies
- Experimental studies, in which I the
investigator get to determine in what you as
participant are going to get. That is what we
call clinical trials (RCTs few subjects). If
we talk about bigger communities
community intervention trials. Field trials
are even bigger (e.g. malaria trials). In
general, assigning people or things to group
and apply some treatment to one of the groups, while the other group does not
receive the treatment.
- Observational studies, where the investigator has no influence on whether you get
your vaccine or not. Thus, we measure or survey members of a sample without trying
to effect them.
Randomized Clinical Trials (RCTs) Observational (postmarketing surveillance (PMS)
limited number of patients large number of patients
Limited time unlimited time
Homogenous population drug-users in practice
Other variable excl. or controlled other influences (e.g. smoking, other drugs,
Nutrition.
Important clinical information that has to be obtained from PMS research:
- Usage and determinants in practice
- Effects in daily practice
- Adverse effects
- Drug interactions
- Usage of drugs for other indications (off-label)
- New applications
- Applied dosage and duration
- Usage/effect in children, elderly, pregnant woman
, - Effect on ‘hard’ endpoint (disease/mortality)
- Effect on population level (for example regarding the corona virus)
- Pharmaco-economics
- Cost
- Compliance
- Cost-effectiveness of interventions
Terminology of the word ‘effect’
- Efficacy: effect in clinical trials or laboratory studies
- Effectiveness: effect in daily practice
- Efficiency : costs in relation to effects
Post-marketing surveillance/phase IV research
- Definition: “monitoring all (anticipated and unanticipated) desirable and undesirable
(adverse)-effect of drugs to human health, after these drugs are released on the
market”.
- Goals is to obtain scientifically data on rational and safe use of drugs. It is obligatory
for pharmaceutical companies to have a ‘Risk Management Plan’ for all drugs that
are released on the market. In the RMP a company explains which studies are
performed to increase knowledge about the risks of drugs.
The institute of medicine has set up some guidelines to better monitoring and reporting on
the drug safety. They enforced the FDA/EMA to have authority on research from
pharmaceutical companies. They also have black triangle on newly approved drugs (these
needs to be studied more intensively). ‘Direct-to-consumer advertising’ prohibited in the
first 2 years after registration.
Who has interest in PMS?
- Patients: wants an effective and safe drug with reliable information.
- Physician/pharmacist: wants reliable and complete information to make a good
decision.
- Insurance company: importance of rational prescribing with regards to cost.
- Government: responsible for registration and population health.
- Industry: wants a good product.
Information sources for PMS (pharmaco-epidemiological research)
- Spontaneous reporting systems: e.g. LAREB
- Routine (administrative) databases: e.g. prescription databases
- Questionnaires/interviews/web-based
- Cohort/physical testing/lab data
