Describing Characteristics of Participant Population

When describing the characteristics of your participant population in human subjects research, the goal is to provide a clear, comprehensive, and ethically-minded picture of who you plan to study. This description is crucial for Institutional Review Boards (IRBs)/Ethics Committees to assess potential risks, benefits, and the appropriateness of protections.

Here's a guide to describing the characteristics of your participant population, broken down into key areas:

Describing Characteristics of Participant Population

1. General Demographics:

• Age Range:


• Specify the minimum and maximum age (e.g., "adults aged 18-65 years," "children aged 8-12 years").


• Justify the age range: Why is this specific range relevant to your research question? (e.g., developmental stage, disease prevalence, cognitive capacity).


• Consider minors: If including participants under 18, detail the plan for parental permission and child assent.


• Gender/Sex:


• Specify if the study is inclusive of all genders/sexes or if it's restricted (e.g., "males and females," "individuals identifying as female").


• Justify any restrictions: If restricting, explain the scientific rationale (e.g., hormone-specific research, disease prevalence).


• Race/Ethnicity:


• Describe the anticipated racial and ethnic composition, especially if targeting specific groups or aiming for diversity representative of the broader population or a specific patient group.


• Justify any specific targeting or exclusion: Explain why a particular racial/ethnic group is targeted or excluded (e.g., health disparities research, genetic predisposition).


• Address representativeness: Discuss efforts to ensure diverse participation or acknowledge limitations if a non-diverse sample is anticipated and justify why.


• Geographic Location:


• Where will participants be recruited from? (e.g., "residents of [city/county]," "patients from [specific hospital]," "online participants from [country/region]").


• Education Level & Socioeconomic Status (SES):


• If relevant to the research question or to understanding participant comprehension/burden, describe the expected range of education levels or SES.


• Consider implications for consent: Lower education levels or SES might necessitate simplified language in consent forms or alternative consent methods.

• General Health:


• Are you seeking healthy volunteers, or individuals with specific health conditions?


• If healthy: Describe the criteria for "healthy" (e.g., "no chronic medical conditions," "not currently taking prescription medication").


• Specific Medical/Psychological Conditions:


• If studying a particular condition, provide details:


• Diagnosis: What is the specific diagnosis? (e.g., "Type 2 Diabetes," "Major Depressive Disorder").


• Severity/Stage: Is there a required severity or stage? (e.g., "mild to moderate depression," "Stage I-II cancer").


• Duration: Is there a required duration of the condition? (e.g., "diagnosed at least 6 months prior").


• Current Treatment: Are participants required to be on certain medications, or free from them? Are there wash-out periods?


• Comorbidities: Are participants with co-occurring conditions included or excluded?


• Disabilities:


• Are participants with physical, sensory, or intellectual disabilities included or excluded? How will you accommodate them?

• Cognitive Function:


• Are participants expected to have typical cognitive function, or are you including individuals with cognitive impairment (e.g., dementia, intellectual disability)?


• If impaired: Detail the degree of impairment and how decisional capacity will be assessed. Describe plans for surrogate consent/assent.


• Developmental Stage:


• If studying children, specify the developmental stages (e.g., "preschoolers," "adolescents"). This impacts how you interact, obtain assent, and present information.

• Explicitly identify if your population includes any groups considered "vulnerable" by regulations (e.g., 45 CFR 46, ICH-GCP).


• Minors/Children: Lack full legal capacity to consent.


• Pregnant Women, Fetuses, Neonates: Unique physiological and ethical considerations.


• Prisoners: Vulnerable due to restricted autonomy, potential for coercion.


• Individuals with Impaired Decisional Capacity: Due to illness, intellectual disability, psychiatric condition, or traumatic brain injury.


• Economically Disadvantaged: May be vulnerable to undue inducement if incentives are disproportionately high.


• Educationally Disadvantaged: May have difficulty understanding complex information.


• Students/Employees/Subordinates of the Investigator: Potential for perceived coercion or undue influence due to power dynamics.


• Terminally Ill: May be desperate for treatment, affecting their ability to refuse.


• Institutionalized Individuals: (e.g., in nursing homes, psychiatric facilities) may have reduced autonomy.


• Undocumented Immigrants: Fear of deportation, exploitation.


• Justify Inclusion: If including vulnerable populations, provide a compelling scientific and ethical justification for why their inclusion is necessary and cannot be achieved with non-vulnerable populations.


• Describe Enhanced Protections: Detail the specific additional safeguards and protections you will implement for each identified vulnerable group (e.g., independent consent monitors, assent procedures, careful assessment of undue influence, specialized consent processes).

• Inclusion Criteria:


• List the specific characteristics participants must possess to be eligible (e.g., "diagnosed with Condition X," "fluent in English," "able to attend in-person visits").


• Exclusion Criteria:


• List the specific characteristics that would make someone ineligible (e.g., "pregnancy," "history of Condition Y," "current use of Medication Z," "cognitive impairment preventing informed consent").


• Justification: For both inclusion and exclusion, provide clear scientific, ethical, or practical justifications for each criterion.

• State the target number of participants you aim to enroll.


• Briefly mention the statistical justification for this sample size, if appropriate (e.g., "based on power analysis," "to achieve saturation in qualitative data").

Example Snippet:

"The participant population will consist of 100 adults (aged 25-50 years), both male and female, recruited from the general community of [City, State] through online advertisements and flyers in community centers. Participants must be fluent in English, have no history of neurological or psychiatric disorders, and be able to provide informed consent. We will aim for a diverse sample representative of the local population's racial and ethnic composition. Individuals with impaired decisional capacity or who are currently pregnant will be excluded due to the cognitive demands of the study tasks and potential unknown risks of the intervention, respectively. No specific vulnerable populations are intentionally targeted, but robust consent procedures will be used to ensure full comprehension by all participants."

By systematically addressing these points, you provide a clear and ethical foundation for your research proposal and demonstrate a thorough understanding of participant protections.