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In medical research, there are several types of clinical trials that are designed according to the objective of the study and the nature of the treatment to be evaluated.
On the other hand, clinical trials are fundamental to precision medicine, as they allow the efficacy and safety of personalised treatments to be rigorously and systematically assessed. By tailoring medical interventions to the individual characteristics of each patient, clinical trials in this field not only improve therapeutic outcomes, but also minimise adverse effects and optimise the use of healthcare resources. This innovative approach transforms clinical practice, facilitating the transition to more effective, safer and patient-centred medicine.
The following is a list of different types of clinical trials, each with specific characteristics that make them essential for addressing various research questions and clinical contexts:
Randomised controlled clinical trials (RCTs)
Objective:
- Compare the effectiveness of a new treatment with a standard treatment or placebo.
Characteristics:
- Randomisation: Participants are randomly assigned to different groups (e.g. treatment group and control group).
- Blind: They can be blind or double blind to avoid bias.
- Control group: One group receives standard treatment or placebo.
Advantages:
- Minimise bias.
- Provides robust evidence of treatment effectiveness.
Ensayos cruzados (Crossover trials)
Objective:
- Compare the effectiveness of two or more treatments in the same participants.
Characteristics:
- Design: Each participant receives multiple treatments at different time periods.
- Wash-out period: Time between treatments to avoid residual effects.
- Self-control: Participants act as their own controls.
Advantages:
- It reduces inter-subject variability.
- Requires fewer participants.
Ensayos adaptativos (Adaptive trials)
Objective:
- Modify aspects of the trial (such as dosing, sample size, inclusion/exclusion criteria) based on data accumulated during the study.
Characteristics:
- Flexibility: Allows for changes in study design based on intermediate results.
- Efficiency: Can accelerate the development of effective treatments and the discontinuation of ineffective treatments.
Advantages:
- Optimise resources.
- Potentially accelerates the approval of effective treatments.
Ensayos Basket (Basket tests)
Objective:
- To evaluate the effectiveness of a treatment in different types of cancer that share the same genetic mutation.
Characteristics:
- Population: Includes patients with different types of cancer, but with a common molecular characteristic.
- Molecular approach: Focusing on the genetics of the tumour rather than its location in the body.
Advantages:
- It allows the development of personalised treatments.
- It can identify subgroups of patients who respond to treatment.
Cohort clinical trials
Objective:
- To study the relationship between exposure to a factor and the development of a disease or condition.
Characteristics:
- Design: Observational, participants are selected according to their exposure to a specific factor and followed over time.
- Comparison: Disease incidence rates are compared between those exposed and those not exposed.
Advantages:
- Useful for studying multiple outcomes from a single exposure.
- Less costly and faster than randomised trials.
Case-control clinical trials
Objective:
- To investigate the causes of a disease by comparing subjects with the disease (cases) with subjects without the disease (controls).
Characteristics:
- Design: Retrospective, comparing previous exposure to risk factors between cases and controls.
- Control selection: Controls are selected to be as similar as possible to cases, except for the presence of disease.
Advantages:
- Good for studying rare diseases.
- Lower cost and time compared to cohort studies;
Pragmatic clinical trials
Objective:
- Evaluate the effectiveness of an intervention in real clinical practice conditions.
Characteristics:
- Design: Similar to randomised controlled trials, but conducted in real clinical settings and with fewer restrictions.
- Approach: Overall results and practical applicability.
Advantages:
- Results more applicable to daily clinical practice.
- It includes a more diverse and representative population.
Non-inferiority clinical trials
Objective:
- Determine whether a new treatment is no worse than a standard treatment by more than a pre-specified margin.
Characteristics:
- Design: Comparative, often similar to randomised trials, but focused on demonstrating that the new treatment is “non-inferior”.
- Non-inferiority margin: Established before the test, it represents the maximum tolerance to the acceptable difference.
Advantages:
- Useful when you want to introduce a safer, cheaper or easier to administer treatment without sacrificing efficacy.
Sequential clinical trials (Sequential trials)
Objective:
- Evaluate the efficacy of treatments through periodic interim analyses and decide on the continuation of the trial based on these results.
Characteristics:
- Design: Includes periodic analysis of data throughout the trial.
- Approach: Allows the trial to be stopped early if clear efficacy or inefficacy is demonstrated.
Advantages:
- It can reduce testing time and costs.
- Minimises patients’ exposure to ineffective or unsafe treatments.
Clinical prevention trials
Objective:
- Research on how to prevent the development of diseases in healthy or at-risk individuals.
Characteristics:
- Design: Can be randomised or non-randomised, focusing on preventive interventions.
- Population: People without the target disease or at high risk of developing it.
Advantages:
- Important for reducing the incidence of disease.
- It can provide effective public health strategies.
Conclusion
The diversity of clinical trials is fundamental to the advancement of medicine. Each type of trial addresses different research questions and clinical contexts, allowing for a more complete understanding of medical interventions.
Each type of trial has a specific design that is adapted to different research objectives and contexts and plays a crucial role in the advancement of medicine.
Sources:
https://www.cancer.gov/publications/dictionaries/cancer-terms/def/basket-trial
https://www.scientific-european-federation-osteopaths.org/diferentes-tipos-de-ensayos-clinicos/