The different types of studies

Many types of clinical studies exist :

Yes, there are many exemples again, but it's interesting, I swear !

Case presentation : an isolated case interesting for its rarity or a particular reaction

This one could show funny deseaeses !

Case series : Retrospective study based on the analysis of clinical cases, no comparison with controls

For sure this one could be boring, but it depends on the case

Case-control study : a retrospective study between two groups, one with a disease (cases) and the other free (controls)

Cohort study : comparison between a group of subjects exposed to a risk, versus an unexposed group

Controlled randomized trials: comparison between two randomized groups, one receiving the treatment studied, the other a placebo or a standard treatment

These are the trials which are the most used

Meta-analysis: recovery of a set of comparable studies and global analysis using statistical tools

These are the Rolls Royce of the trials !

Intervention/Non-Intervention Research

We tell you about clinical research from the start, but we haven’t even told you that there are different types of clinical research!

Don’t worry we’ll do basics ;)

In fact there are two main groups : intervention research and non-intervention research.

See, it is not that hard to remember! Let’s go further…

Intervention Research:

Intervention research are research on a medical treatment, on a surgical method, on a medical or surgical material (a new syringe, a new breathing apparatus for example) and so on.

For this type of research, there is an act on the person who participates in the research. It means that the patient is given a medication that will act on his/her organism or he/she will get a medical or surgical act. In brief you do something to the patient, in addition to its usual medical treatment, that can have consequences for him/her.

To sum up, they do or give you something that can have consequences on you, isn’t it great? J

 Non-Intervention Research:

Here you do not do anything to the patient that is not done for his/her usual medical care. It is observational research or research for in vitro diagnostics.

Just so that you will understand the last one: in vitro diagnostics are the research which test reagents used by doctors to diagnose patients.
There you don’t have to worry about the impact on yourself as they won’t do anything that wouldn’t have been done anyway.
 
There are more detailed information on the different kind of research but it’s enough for today J

Main actors of a clinical trial

Different people interact during a clinical trial, they all have different roles, but of course depending on the firm or the exact field you work in it might change… It wouln’t be fun if it was simple!!

So here are the main actors and their roles in general.

 The project leader:

He is the one who leads the whole team, the manager. The project leader is involved early in the product life.
He writes the mains documents used for the clinical trial : the plan, the protocol, the report.
He is in charged of finding the sites where the study will be done.
He also has to maintain the budget, the timelines, and to succeed with the study! Sounds easy, doesn’t it?

The Clinical Research Associate:
The Clinical Research Associate, or CRA, is in charge of the good progress of the study.
He sets everything up in each clinical trial site involved in the study, explains to the hospital team what they will have to do, all the details of the protocol and so on.
After the study has begun, he comes regularly to check if everything is done following the protocol, and if this is not the case, he has to make what is necessary to correct it.

The Data Manager Associate:

The Data Manager is in charge of the data processing, verify and freeze the database (a frozen database can’t be modified, by anyone).

The Biostatistician:
The biostatistician does the statistical analysis required in the protocol on the frozen database.

 The investigator:
Most of the time, the investigator is a doctor. He is selected by the project leader to conduct the study in his hospital. He is responsible for including patients and for their follow-up.
Of course he is not doing this just for fun, he signs a contract and his hospital receives money!

The pharmacist:
The pharmacist, is most of the time the hospital ‘s one, stores the drug and deliver it to the patients. He also gets the empty (or not) boxes back to evaluate the compliance of patients. For example: when a patient gives back the previous month drug box if he had taken all the drug, it should be empty. If it is not you will know how many times he did not take his medication, 25% of the time, 50% ? (you wonder why? Well if a patient takes his medication every other day, no wonder why it doesn’t work!!)

There are a lot of other people playing a role in a clinical trial, and some of those I present will have a different job description depending on where they work but this will give you an idea of what kind of people are part of the clinical trial team J

Clinical trials bias

A bias is a cause of statistical analysis errors related to the experimentation method.

Yes, we are making mistakes like everyone, but not as much, I promise ...

Attrition bias

They are due to differences between groups. They are linked to outputs test or treatment interruptions.

For example, we have 2 groups of 100 participants : group A is treated, group B received a placebo.

I know, there are numbers, but it won’t be complicated !

In group A there are 50 outputs due to treatment intolerance, and 50 improvements.

In group B, 0 output, 50 improvements, 50 stagnation.

If we do not analyse outputted patients, we have 100% improvement in Group A against 50% in group B.

However if we analyse all patients, we do not observe any difference.

I told you it wasn’t hard was it ?

Selection bias

It is due to a difference in the composition between the treated and control groups. This can influence the results of the study. Randomization is the only way to avoid selection bias.

Monitoring bias

It is related to differences in the support between the treated group and control group.

Quality criteria

There are several quality criteria for a clinical trial :

Ethics

An ethical criterion is essential in any clinical trial.

Volunteers participating in clinical studies must be informed of possible risks and give an "informed consent".

We warn you about what will happen to you, isn't it great ?

In France, the advice of a committee for the protection of persons is required.

Controlled study

A control group is needed to validate the effectiveness of a procedure. Indeed, if a study of a drug shows 90% healing, someone might dramatically early conclude the effectiveness of the treatment.

What a mistake!!

In fact, if in the control group (which is not treated), the cure rate is 100%, the conclusion will be reversed!

Smart, isn't it ?!

Randomized study

The distribution between the two groups must be done by drawing lots.

Blinded study

It is preferable the subject doesn’t know which group he is assigned to and which treatment he receives, for example, an active drug or placebo. That is called a single blind.

Yeah, that could be disturbing, but we’ve got something better just after :

When the investigator also doesn’t know which patient is in the control group and which group is in the other, it is called a double blind study. That’s the best !

Multi-centered study

A trial taking place simultaneously in several different locations allows the study of a larger number sample and a larger diversity in the population included.

Monitoring Committee and Monitoring

Or as we say in English, yes, you're everywhere ! Data Monitoring Committee (DMC) or Data Safety and Monitoring Board (DSMB).

It is a group of independent experts who monitor the data in terms of patient safety.