What are the inclusion and exclusion criteria for a clinical trial enrolling adults aged 18‑80 years with a confirmed diagnosis of the target condition?

Inclusion and Exclusion Criteria for Clinical Trials in Adults Aged 18-80 Years

Standard Age Criteria

The minimum age for clinical trial enrollment should be 18 years (legal age of consent), and an upper age limit of 80 years is commonly used but increasingly discouraged as it lacks scientific justification and excludes a population that would benefit from treatment. 1, 2

Age-Related Considerations

• Minimum age: 18 years is standard across most trials, representing the legal age for informed consent 1
• Upper age limits: While historically set at 80-85 years in many trials (particularly stroke trials like ANGEL-ASPECT, SELECT2, and TESLA), current guidelines recommend NOT imposing maximum age restrictions 1, 2
  • Older patients (>80 years) have increased hemorrhage risk in some interventions, but clinical efficacy often persists 1
  • Age-based exclusions affect 72.1% of trials overall, with 38.5% excluding older adults 3
  • The elderly are the highest consumers of medical interventions yet remain systematically underrepresented 4

Core Clinical Inclusion Criteria

Confirmed diagnosis of the target condition with objective documentation is essential, along with:

• Baseline neurologic/functional assessment using validated scales (NIHSS, modified Rankin Scale, Bartholomew Index for stroke trials) 1
• Defined time window from symptom onset or last known well to treatment initiation 1, 2
• Adequate performance status: Most trials use ECOG PS 0-2, though this should not automatically exclude PS2 patients 5, 6
• Clinical signs consistent with the target condition requiring intervention 1

Standard Exclusion Criteria

Medical Contraindications (Common Across Trials)

The following represent strongly justified exclusions 1, 2, 7:

• Pregnancy and lactation (excluded in 82% of hepatic/renal trials, 39.2% overall) 3, 7
• Severe renal dysfunction (79% of trials exclude based on renal criteria) 7
• Severe hepatic dysfunction (82% of trials exclude based on hepatic criteria) 7
• Active infectious diseases requiring specific consideration 7
• Coagulation disorders/thrombocytopenia (though some stroke trials include with caution) 8
• Recent major surgery (though case series show acceptable risks in some contexts) 1
• Contrast allergies (for imaging-based trials) 2

Conditions Requiring Individualized Assessment

These are frequently used but often poorly justified exclusions 3:

• Concomitant medications: Excluded in 54.1% of trials, often without strong justification 3
• Medical comorbidities: Used in 81.3% of trials, but only 47.2% of exclusion criteria are strongly justified 3
• Cognitive impairment: Should be assessed objectively rather than categorically excluded 5
• Life expectancy <12 months: Appropriate for trials but should trigger palliative care discussion 9

Functional and Cognitive Requirements

Performance status should not be the sole determinant of eligibility, particularly in older adults 6:

• ECOG PS ≤2 is reasonable for most therapeutic trials 5, 6
• PS2 patients should NOT be automatically excluded from trials of highly effective targeted or immunotherapies 6
• For older adults (≥65 years), geriatric assessment tools provide better functional evaluation than PS alone 6
• Cognitive limitations should be determined by objective testing, not subjective assessment 5

Imaging and Laboratory Requirements

Baseline Imaging 1, 2

• Non-contrast CT or MRI to establish diagnosis
• Vascular imaging (CTA/MRA) when relevant
• Perfusion/diffusion studies as protocol-specified

Laboratory Thresholds 10, 7

• Complete blood count with platelets
• Coagulation studies
• Renal function: Specific thresholds should match drug metabolism/toxicity profile
• Hepatic function: Thresholds should be scientifically justified, not arbitrary
• Growth factor/transfusion-free periods: As specified by protocol 10

Critical Pitfalls to Avoid

1. Overly restrictive age limits: Only 1.7% of trials focus on older adults despite their disease burden 5, 11
2. Blanket PS2 exclusions: These patients may benefit significantly from targeted therapies 6
3. Unjustified comorbidity exclusions: 47.2% of exclusion criteria lack strong justification 3
4. Inadequate reporting: 12% of trials fail to report exclusion criteria entirely 3
5. Gender bias: Despite no formal gender exclusions, men comprised 62% of mixed-gender trial enrollment 7

Special Populations Requiring Consideration

The following groups are systematically underrepresented but should not be categorically excluded 8:

• Pregnant women (with appropriate safety monitoring)
• Patients with controlled HIV infection
• Those with prior/concurrent malignancies
• Patients with mild organ dysfunction
• Individuals with psychiatric or cognitive disabilities (unless affecting informed consent) 12

Broad investigator discretion clauses appear in 85.4% of oncology trials and may disproportionately exclude vulnerable populations, particularly those with psychiatric or cognitive disabilities 12. These discretionary criteria should be minimized and clearly justified when used.