Who Can Participate in Clinical Trials? 

Understanding Eligibility: Inclusion vs Exclusion

Clinical trials are designed with clear, structured criteria to determine who is eligible to participate. These guidelines ensure that the study results are accurate, safe, and applicable to the target population. Eligibility criteria are generally grouped into two main categories: inclusion criteria and exclusion criteria.

What Are the Inclusion Criteria?

Inclusion criteria refer to the set of characteristics that a person must meet to be considered for a clinical trial. These conditions are used to ensure the participants closely match the study objectives and help researchers measure the effects of a treatment accurately.

Common inclusion criteria may include:

• Age Range
  Trials may be limited to specific age groups (e.g., 18 to 65 years) based on the condition or treatment under investigation.
  
• Gender
  Some studies focus exclusively on males or females, particularly when a condition or treatment is gender-specific.
  
• Relevant Medical History
  Participants may need to have a documented history of the medical condition being studied, such as chronic joint pain or Type 2 diabetes.
  
• Confirmed Diagnosis
  Eligibility often requires a formal diagnosis of a condition like IBS-D (Irritable Bowel Syndrome with Diarrhea), gout, or NASH (Nonalcoholic Steatohepatitis).
  
• Lab Results and Physical Health Parameters
  Clinical trials often require lab results (such as blood tests or liver enzyme levels) to fall within a certain range. Physical examination findings like blood pressure or BMI may also be considered.

What Are Exclusion Criteria?

Exclusion criteria identify characteristics or conditions that disqualify a person from participating in a study. These guidelines are primarily in place to protect participant safety and maintain the integrity of the study data.

Common exclusion criteria may include:

• Certain Comorbidities
  People with serious, uncontrolled health conditions such as uncontrolled hypertension, severe heart disease, or advanced kidney disease may be excluded due to elevated health risks.
  
• Pregnancy or Breastfeeding
  Pregnant or nursing individuals are typically excluded from studies, as investigational treatments may pose unknown risks to fetal or infant health.
  
• Use of Specific Medications
  Certain drugs may interfere with the study medication, or participants on conflicting treatments may skew results.
  
• Non-Compliance History
  Participants with a history of missing appointments or not following study protocols may be excluded to ensure reliable data collection.
  

Here’s a table summarizing examples:

Condition	Likely Inclusion	Likely Exclusion
Type 2 Diabetes	Diagnosed for 6+ months, stable medication	Uncontrolled glucose, insulin use
Gout	Recurrent flares, elevated uric acid	Renal impairment, multiple meds
IBS-D	3+ months of symptoms, diagnosis by doctor	Inflammatory bowel disease, recent antibiotics
Obesity	BMI > 30, sedentary lifestyle	Active weight-loss medication use

For individuals with metabolic conditions and a risk of liver disease, the NASH fatty liver clinical trial at Quality Research offers targeted opportunities to participate with free liver scans and diagnostic support.

Health Screening & Diagnostics

Before enrollment, all potential participants undergo a thorough screening process to ensure they meet the trial’s specific criteria. The screening phase usually includes:

1. Medical History Review:

• Past and current diagnoses
  
• Medication lists
  
• Family history relevant to the trial condition
  

2. Vital Signs & Physical Exam:

• Blood pressure
  
• Heart rate
  
• Height and weight (for BMI)
  

3. Laboratory Testing:

• Blood panels (CBC, liver enzymes, cholesterol)
  
• Urinalysis and pregnancy testing if applicable
  

4. Diagnostic Imaging:

• Fibroscan or blood fibrosis test for liver function assessment (commonly used in NASH trials)
  
• EKG or other condition-specific tools
  

These diagnostics help confirm eligibility and provide a baseline before introducing any study medication. Participants in specialized GI studies, such as the IBS-D clinical trial, also complete symptom tracking diaries and GI assessments as part of initial data collection.

When You Might Not Qualify

Not every volunteer is accepted into a clinical study, even if they have the condition being researched. Trials aim to produce the clearest data possible, so strict exclusion criteria are necessary to reduce risks and prevent data distortion.

Common Disqualifiers Include:

• Pregnancy or breastfeeding: Most trials exclude pregnant individuals due to unknown fetal risk
  
• Recent medication changes: New drug regimens within the past 30 days can skew data
  
• Multiple chronic illnesses: Complications like kidney or heart failure may elevate health risks
  
• Behavioral Factors: Substance abuse history or poor adherence in past studies
  

For example, those experiencing recurring joint pain who are not currently taking multiple medications might consider the gout clinical study, which has a clear, structured qualification process.

Always be honest during pre-screening—transparency helps protect your health and ensures high-quality research outcomes.

FAQ: 

 Can healthy people join clinical trials?

 Yes. Many Phase I trials or prevention studies seek healthy volunteers to assess drug safety.

Do I need a referral from my doctor?

No. You can apply directly through the study center or website.

Can I still take my regular medications?

 It depends. Some studies allow maintenance meds, while others require a washout period.

What if I don’t qualify now?

 You may be eligible for future trials. Quality Research keeps potential volunteers informed about upcoming studies.

 Are there age restrictions?

 Yes. Each study has its own age range, but most include adults 18 to 65. Some may target older adults or specific age brackets.

Conclusion

Eligibility for clinical trials in San Antonio is determined by medical, demographic, and lifestyle factors. Whether you’re managing a chronic illness or simply interested in advancing medical science, your participation could make a lasting impact. Quality Research is committed to guiding participants through every stage of the process—from pre-screening to post-trial follow-up.

To explore active trials and find out if you qualify, please visit the Quality Research homepage or contact the team for personalized support.