Establishing safety and efficacy is essential to the approval of pharmaceutical interventions and treatments. The clinical trial process is designed to investigate medicinal products under investigation prior to approval by regulatory authorities and distribution to the general public. This quick and easy guide explains different types of clinical trials and how the process is conducted.
What is a Clinical Trial?
According to the National Institute of Health, clinical trials are research-based studies conducted to evaluate a medical, behavioural, or surgical intervention. Along similar lines, the clinical trial definition, according to the European Union, is the establishment of scientifically-controlled studies conducted on humans to confirm or establish the effectiveness and safety of medicinal products under investigation.
Clinical trials or studies are typically divided into two types: interventional and observational. The purpose of an interventional trial is to discover the effects of a specific intervention or treatment. Participants are placed in different treatment groups during an interventional trial to allow researchers to compare the results.
In contrast, observational studies aim to determine the effects of specific protocols on participants in varying situations. Observational studies include cohort studies, case-control studies, and cross-sectional studies. During this type of clinical trial, researchers observe the people taking part while not playing any role in influencing treatments. Participants in observational studies are typically not separated into groups.
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Features of EU Clinical Trial Processes
Features of the clinical trial process in the EU include:
- Streamlined application procedures conducted in a single EU database and portal
- Registration of applicants prior to assessment
- Standard authorisation procedure to allow a faster and more comprehensive evaluation across all countries in the EU
- Extension of silent agreement principle to the authorisation process that gives legal certainty to researchers and sponsors, specifically for small to medium enterprises and academics
- Strengthened transparency for data produced in clinical trials
Types of Clinical Trials
There are different types of clinical trials among both observational and interventional studies that include:
Pilot and Feasibility Studies
Feasibility studies are conducted to assess if a main study is possible by determining the participation rate, length of study, collection methods, and analysis methods. Pilot studies are smaller-scale versions of a primary study designed to test if the components of the larger study work well together. When used together, pilot and feasibility studies help researchers determine if a more extensive study is possible.
Screening trials
Screening trials test people for early signs of a disease before it occurs. Researchers can plan screening to determine the reliability of tests, or to determine if there is a benefit to finding the conditions before their progression.
Prevention trials
Prevention trials specifically investigate if a specific intervention will effectively prevent a condition.
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Multi-arm multi-stage (MAMS) trials
A multi-arm trial combines several treatment groups (arms) with a standard treatment (control) group. While the standard/control group stays constant, the arms group can change as the study progresses, and researchers may stop recruiting once they have results or determine the treatment does not work.
Cohort studies
A cohort study follows a group of people over a period of time, and is often used to discover longer-term risk factors.
Case-control studies
Case-control studies work opposite to cohort studies, whereby researchers recruit groups that have a disease and a control group that is disease-free. Over time, the research team observes how participants in each group are exposed to specific risk factors.
Cross-sectional studies
Cross-sectional studies are carried out at a specific point in time or over a short time period. Researchers use these studies to determine which participants are exposed to particular risk factors to see if there are any links.
Treatment trials
Treatment trials test pharmaceutical interventions in stages or phases. Early phases aim to determine safety and side effects, while later phases aim to discover treatment efficacy. Recent examples include the Pfizer COVID-19 vaccine clinical trials, Alzheimer’s disease clinical trials, and clinical trials Active Pharmaceutical Ingredients (APIs), and other specialty pharmaceutical chemicals.
Clinical Treatment Trial Phases
Phases in treatment trials are typically divided into four phases as follows:
Phase 1 Clinical Trial
During phase 1 of a clinical trial, researchers test the safety, side effects, dosages, and timing of new treatments. Administration methods are also tested during this phase to determine treatment effects.
Phase 2 Clinical Trial
Phase 2 clinical trials typically provide more information about treatment safety and effectiveness.
Phase 3 Clinical Trial
Phase 3 clinical trials aim to discover the effectiveness of a treatment compared to an existing treatment. Typically, phase 3 clinical trials are conducted once phase 1 and phase 2 clinical trials are completed and goals are achieved.
Phase 4 Clinical Trial
Phase 4 clinical trials study side effects caused by the treatment following its approval. This stage of the treatment trial process aims to look for side effects not observed in earlier trials, in addition to determining how the treatment works in the long term. Phase 4 trials are also referred to as post-marketing surveillance trials.
Clinical Trial Diversity
Medical, surgical, and behavioural interventions can have different effects on individuals depending on genetics, age, health, and other physical factors. Therefore, clinical trial diversity of participants based on age, gender, weight, race, and ethnicity is essential to obtain data on safety and efficacy for wide-scale medical interventions marketed to large populations.
Clinical Trial Retention
Clinical trial retention refers to the process, tactics, and overall strategy of keeping participants enrolled in clinical trials without discontinuing participation and dropping out. Common issues for stopping participation include scheduling conflicts, physical problems, commuting issues, financial constraints, fear, and reduced interest.
Tips to Improve Clinical Trial Retention
Some tips to improve clinical trial retention include:
- Effectively communicating expectations
- Improving study transparency
- Remote data collection strategies
- Providing feedback in real time
Improving participant retention is critical to clinical trial management in order to maintain budgets, obtain clinical trial data, and prevent delays in trial completion.
Clinical Trial FAQ
Phase 3 trials can last between one and four years.
Diversity in clinical trials can be improved through recruitment in areas with diverse residents, providing funds for travel, and employing staff that speak multiple languages.
A pivotal clinical trial is a type of clinical study that aims to demonstrate drug efficacy in order to obtain regulatory marketing approval.
