Is the Canadian Triage and Acuity Scale effective for identifying and enrolling vulnerable patients such as older adults, cognitively impaired individuals, or socially disadvantaged groups into clinical trials?

The Canadian Triage and Acuity Scale is Not Designed for Clinical Trial Enrollment

The Canadian Triage and Acuity Scale (CTAS) is a five-level emergency department triage tool designed to prioritize acute care based on urgency, not to identify or enroll vulnerable populations into clinical trials. 1 The question appears to conflate emergency department triage with clinical trial recruitment—two entirely separate processes with different objectives.

What CTAS Actually Does

The CTAS functions as an emergency department prioritization system with demonstrated reliability (pooled coefficient 0.672, substantial agreement) for sorting patients by acuity level from resuscitation (level 1) to non-urgent (level 5). 2

• Interrater reliability is good with quadratic weighted kappa of 0.74 in pediatric settings and 0.596-0.604 in adult community emergency departments. 3, 4
• The tool correlates with severity markers including hospitalization rates (30% for level 2,8.3% for level 3,2.3% for level 4) and healthcare resource utilization. 4
• CTAS captures acute presentations through clinical indicators like pain scale, chest pain, musculoskeletal injury, respiratory illness, and headache—accounting for 60-68% of emergency visits. 3

Why CTAS Cannot Identify Trial-Eligible Vulnerable Populations

Emergency triage and clinical trial enrollment serve fundamentally different purposes. CTAS assigns acuity based on immediate medical urgency, not on the characteristics that define vulnerable trial populations.

• Vulnerable populations for trials include older adults with frailty, cognitive impairment (assessed via geriatric assessment tools), comorbidity burden, functional limitations, and socioeconomic disadvantage. 5
• CTAS does not assess geriatric vulnerability scores, functional status (ADLs/IADLs), cognitive screening (Mini-Cog, MoCA), frailty indices, or social determinants of health—all essential for identifying trial-appropriate vulnerable patients. 5, 6
• Trial enrollment requires comprehensive geriatric assessment including functional status, comorbidities, nutritional status, psychological state, social support, and cognitive function to predict treatment tolerability. 5

What Actually Works for Trial Enrollment of Vulnerable Populations

Guidelines explicitly recommend broad inclusion criteria with appropriate stratification for frailty and comorbidities, not emergency triage tools. 5

• Use validated vulnerability scoring tools such as the geriatric vulnerability score (GVS) specifically developed for oncology trial populations. 5
• Implement geriatric assessment (GA) at study entry as a predictor of treatment tolerability, incorporating functional status (Pfeffer FAQ, DAD), cognitive screening (validated instruments), and comorbidity indices. 5, 6
• Apply enrichment designs that specifically target high-risk populations based on pre-specified frailty or vulnerability criteria, or use marker-by-treatment interaction designs that stratify by toxicity risk. 5
• Address system-level barriers including provider bias (older age alone should not exclude enrollment), study design barriers (overly restrictive eligibility criteria), and ensure equitable access across ethnic and socioeconomic groups. 5

Common Pitfall

Attempting to repurpose emergency department triage tools for clinical trial screening will fail because CTAS measures acute illness severity in minutes-to-hours timeframes, while trial eligibility for vulnerable populations requires assessment of chronic functional status, cognitive capacity, social support, and treatment tolerance over weeks-to-months. 1, 5 These are orthogonal constructs that cannot be bridged by a single tool.