A clinical trial is a research study in volunteer human subjects to determine the safety and efficacy of new treatments, screening methods, preventive techniques, or diagnostic methods for a disease. New devices, drugs, procedures, and medical innovations must be thoroughly tested to ensure that they are safe and effective for human patients. Human trials are only conducted after both laboratory and animal studies show promising results.
The ultimate goal of HIV/AIDS clinical trials is to find more effective and safer ways to diagnose, treat, and prevent HIV/AIDS.
Researchers develop ideas for clinical trials when they have a hypothesis about something. For instance, if there have been reports of pregnant HIV patients who received HIV treatment and did not pass the virus on to their babies, researchers may choose to investigate the safety and effectiveness of anti-HIV drugs (antiretrovirals) during pregnancy.
Before a clinical trial is conducted, a specific set of rules, called protocol, is developed.
A protocol includes information on types of patients who can participate in the trial, the schedule of tests, procedures, medications/dosages, and length of the study.
During a clinical trial, the researchers monitor the participants' health to determine the safety and effectiveness of treatment.
CLINICAL TRIAL PHASES
Phase I: In phase I clinical trials, researchers test a new drug or treatment in a small group of 20-80 patients for the first time. The goal is to evaluate the drug or treatment's safety, determine a safe dosage range, and identify side effects.
Phase II: Phase II clinical trials study the effects of a drug or treatment in a larger group of 100-300 patients. During this phase, researchers aim to determine the drug or treatment's efficacy and further assess its safety.
Phase III: During phase III trials, researchers study the effect of a drug or treatment in large groups of 1,000-3,000 patients. This type of trial is used to confirm the drug or treatment's effectiveness and monitor side effects. The drug or treatment is also compared to commonly used treatments and researchers collect information that will help ensure that the drug or treatment is used safely.
Phase IV: Phase IV clinical trials are performed after the drug or treatment has been marketed to the general public. These studies are conducted to collect information on the drug or treatment's long-term effects and side effects in various patient populations.
TYPES OF CLINICAL TRIALS
General: Many clinical trials have what is called a control group. A control group is a group of patients that serve as the basis of comparison when evaluating a new drug or treatment. The control group usually receives a placebo, which is an inactive drug (sometimes called a sugar pill) that has no treatment value. In some studies, the control group may receive the standard drug/treatment or no drugs/treatment.
The results of both groups of patients are evaluated. This allows researchers to determine whether the experimental drug or treatment actually had an effect on patients when compared to those who did not receive the experimental drug or treatment.
The gold standard for medical research is the double blind, randomized, controlled trial, which is described below.
Blinded study: During a blinded study, participants do not know whether they are part of the experimental or control group. Patients in the experimental group receive the drug or treatment that is being tested. Depending on the individual study, patients in the control group may receive a placebo or standard treatment.
Controlled trial: During a controlled trial, the experimental agent is compared to either a placebo (inactive therapy) or the standard effective treatment.
Double-blind study: During a double-blind study, neither the participants nor the researchers know which patients are receiving the experimental drug or treatment. This type of study is performed so neither the researchers nor the participants have expectations about the treatment that could influence the outcome.
Open label clinical trial: During an open label clinical trial, both the researchers and participants know which patients are receiving the experimental drug or treatment.
Randomized trial: If a trial is randomized, the participants are randomly selected to either be in the experimental group or control group. This helps ensure that subjects in both groups are comparable or as similar as possible.
Systematic review and meta-analysis: After several studies have evaluated a particular drug or treatment, researchers may conduct a systematic review or meta-analysis. These reviews provide summaries of the trials that have been performed to date.
MEASURING THE POWER OF CLINICAL TRIALS
General: The power of a trial refers to the ability of a study to produce statistically significant results. Studies with a large number of participants that last a long period of time are more likely to produce statistically significant results than small, short-term studies.
Statistically significant results: If the results of a study are statistically significant, this means the results are not likely to be the result of chance alone. In research articles, the authors use what is called the P value to indicate the chance that an observed result was due to chance. If the P value is lower than 0.05 (p<0.05), it is traditionally accepted as an indication of statistical significance. This means that the likelihood is less than five percent that the observed difference between study groups was simply the result of chance. For instance, if the majority of HIV patients taking antiretrovirals lived longer compared to HIV patients who received no treatment, and the results are statistically significant, the medication has been shown to be beneficial for HIV patients.
Study size and length: The more study participants and the longer the study, the more power the study has. Larger and longer studies generate more data than smaller, shorter studies. This makes it less likely that the results are simply due to chance.
REPORTING TRIAL RESULTS
Medical Journals: After a clinical trial is performed, the gold standard for presenting the results is publication in a peer-reviewed professional journal. These journal articles are reviewed by experts in the same field as the authors of the studies. Journal articles contain five major sections: abstract, introduction/background, design and methods, results, and discussion.
The abstract is a short summary of the research article. It includes the researchers' objective and goals of the study. It also briefly summarizes each section of the paper and includes the authors' conclusions.
The introduction/background section usually provides a statement that explains the issue that was investigated. It also explains why the study was performed and what the researchers hypothesized (expected to prove).
In the design and methods sections, which may be combined, the researchers explain how the study was carried out. This section includes detailed information about the study participants, the treatments used, the tests that were performed, and how the data was assessed.
The results section provides detailed information of all the data that was collected. This section typically includes graphs, charts, tables, and/or pictures, as well as a statistical analysis of the results.
In the discussion section, the authors explain their interpretations of the results. Here, researchers explain what the results mean and how they might affect clinical practice. Authors also explain whether their initial hypothesis was confirmed, as well as potential limitations of the study and suggestions for additional research.
Scientific conferences: In addition to medical journals, researchers may also present their findings at conferences related to their fields of study. Some of the most significant HIV/AIDS conferences include the annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), the annual Conference on Retroviruses and Opportunistic Infections, and the biannual International AIDS Conference.
Researchers submit their study abstracts before the conference. Lead authors of the most interesting or groundbreaking studies are presented. Additional studies are typically presented on posters. Depending on the size of the conference, abstracts from oral and poster presentations may be published and/or available online.
ENROLLING IN CLINICAL TRIALS
Who can participate: All HIV patients can volunteer to participate in clinical trials. However, each clinical trial has unique guidelines for who can participate in the study, called criteria. Patients interested in enrolling in a particular study must meet the criteria. This helps ensure the patient's safety and helps ensure that researchers are able to accurately prove or disprove their hypotheses. Factors that allow a patient to enroll in a clinical trial are called inclusion criteria, and factors that prevent a patient from enrolling are called exclusion criteria. Criteria may include or exclude patients based on factors such as age, medical history, gender, current medications, co-existing illnesses, and overall health.
Weighing the pros and cons: Participation in clinical trials is completely voluntarily, and the decision should only be made after the patient has carefully considered the potential health benefits and risks. This risks and benefits will be different for each trial and each individual patient. It is important for patients to consult their personal healthcare providers and family members before deciding whether or not to participate in a clinical trial.
Patients will meet with the researcher(s) before being enrolled in the study. This allows patients to ask any questions and address any concerns about participating. Patients should consider writing down questions ahead of time, asking a friend or family member to join them for support, and/or recording the discussion.
Participating in a clinical trial allows patients to take an active role in their healthcare. Participants gain access to new treatments that are not available to the public and participants help others by contributing to medical research. However, risks of participating in a trial may include side effects or adverse reactions, the treatment may not be effective, the trial may take up a lot of the patient's time, and participation may require hospital visits or involve complex treatment plans.
Safety: The federal government has guidelines and safeguards to protect participants in clinical trials. All clinical trials in the United States must be approved and monitored by an Institutional Review Board (IRB) to ensure that the risks are minimal and worth the potential benefits. An IRB is an independent committee that consists of physicians, statisticians, community advocates, and other professionals.
During the trial: The process of each clinical trial is different. The research team generally includes doctors, nurses, and other healthcare professionals. Participants should closely follow the trial's protocol to ensure their safety. Participants are evaluated at the beginning and end of the trial, and their health is monitored continually throughout the trial. Some researchers will stay in touch with participants after the study to perform follow-up tests and/or questionnaires.
While enrolled in the trial, patients should continue to regularly visit their primary healthcare providers. This helps ensure that the clinical trial protocol is not interfering with the patient's regular medications or treatments.
Leaving early: Participants can choose to leave a clinical trial at any time. Patients who want to stop participating should let the researcher(s) know why they are leaving the trial.
Payment: Some clinical trials pay participants to enroll in the study, while others do not. Some trials will reimburse participants for expenses associated with the trial, such as transportation costs, accommodations, meals, or childcare. Potential study participants can discuss whether payment is offered when they meet with the researcher(s). Payment is often not offered if a patient leaves the trial early or does not adhere to protocol.
FINDING HIV/AIDS CLINICAL TRIALS
: AIDSinfo is a U.S. Department of Health and Human Services (DHHS) project that provides current, federally-approved information about HIV/AIDS research, treatment, and prevention to patients, healthcare providers, and the general public. This website contains information about ongoing HIV/AIDS clinical trials that are both federally and privately funded.
: ClinicalTrials.gov provides patients and medical professionals with information about clinical trials that are recruiting study participants. This database, which is updated regularly, contains information on more than 36,100 clinical studies around the world that are both federally and privately funded. Each listing includes the trial's purpose and eligibility requirements.
: MEDLINE, which is a database of more than 10 million references, is a comprehensive source of peer-reviewed medical literature. This database provides free access to research abstracts. Patients can click on the journal links to purchase the full-text of articles. Additionally, patients can visit their local library to attain copies of specific journal articles.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
- AIDSinfo. http://aidsinfo.nih.gov. Accessed May 29, 2007.
- Aronson JK. What is a clinical trial? Br J Clin Pharmacol. 2004 Jul;58(1):1-3. .View abstract
- ClinicalTrials.gov. http://clinicaltrials.gov. Accessed May 29, 2007.
- National Institute of Allergy and Infectious Diseases. www3.niaid.nih.gov. Accessed May 29, 2007.
- Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com. Copyright © 2007. Accessed May 29, 2007.
- San Francisco AIDS Foundation. www.sfaf.org. Accessed May 29, 2007.
- The Body: The Complete HIV/AIDS Resource. www.thebody.com. Accessed May 29, 2007.
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