CORE-ALI Sets Out to Standardize Outcomes in Acute Lower Limb Ischaemia
Acute lower limb ischaemia remains one of vascular medicine’s most time-sensitive emergencies. The condition can cost both limb and life within hours, yet the evidence base guiding treatment still suffers from a basic problem: studies do not measure the same outcomes in the same way. CORE-ALI is designed to address that gap by building a pan-European Core Outcome Set, or COS, for acute lower limb ischaemia, with the goal of making future trials easier to compare, synthesize, and use in practice.
The protocol is built around a simple but consequential premise. When one study emphasizes amputation, another tracks technical patency, and a third focuses on survival or symptom relief, no clear common language emerges for clinicians, guideline writers, or patients trying to judge which treatment matters most. In a field defined by urgent intervention and high stakes, inconsistent outcome reporting weakens the value of even well-run clinical research.
Why a Core Outcome Set Matters in Vascular Emergency Care
Acute lower limb ischaemia is not a condition where outcome selection can be left to chance. Revascularization, thrombolysis, thrombectomy, bypass surgery, and hybrid strategies may all be used, but the same intervention can look favorable or disappointing depending on which endpoint is chosen. A trial centered on vessel patency may miss the functional consequences of tissue loss, pain, mobility decline, or long-term disability. A study focused only on limb salvage may overlook mortality, reintervention, or the patient experience of recovery.
A Core Outcome Set is meant to correct that imbalance. By agreeing on a minimum group of outcomes that every study in the area should report, investigators can compare interventions more reliably and reduce selective reporting. For a disease in which decision-making often happens under severe time pressure, that standardization carries direct clinical value.
The protocol also places patient-centred outcomes on equal footing with traditional clinical measures. That is especially important in vascular emergencies, where a technically successful procedure may still leave a patient with major pain, reduced independence, or prolonged rehabilitation. The study’s design acknowledges that a limb-salvage endpoint alone does not fully describe recovery.
Mixed-Methods Design Across European Health Systems
CORE-ALI will use a structured, multi-phase mixed-methods approach guided by the COMET initiative and the COS-STAR reporting standards. The first phase begins with semi-structured interviews involving patients, clinicians, and policymakers drawn from diverse European healthcare systems. Those interviews will generate a preliminary list of outcomes through thematic analysis.
The use of qualitative methods is not a formality. Acute lower limb ischaemia spans emergency medicine, vascular surgery, interventional radiology, and rehabilitation, and each group may define success differently. Patients may prioritize pain relief, walking ability, or avoidance of major amputation. Clinicians may emphasize procedural success, limb salvage, or short-term survival. Policymakers may focus on outcomes that can support health-system planning and equitable care. The protocol is built to capture those differences before consensus is attempted.
A multilingual structure will support participation across countries and healthcare settings. That matters in a European project, where language barriers can quietly distort whose priorities enter the final outcome list. The protocol also specifies GDPR-compliant platforms for data handling, an important safeguard when interviews and Delphi rounds involve cross-border participation and sensitive health information.
Delphi Rounds Will Narrow the Outcome List
Once the initial list of candidate outcomes is assembled, CORE-ALI will move into a multi-round Delphi survey, anticipated to include two to three rounds. Delphi methodology is commonly used when no universally accepted standard exists and structured consensus is needed. Participants score and refine outcomes over repeated rounds, with feedback allowing the group to move toward agreement.
In this study, quantitative data from the Delphi process will be analyzed with descriptive and non-parametric statistical methods. The design leaves room for outcomes to rise or fall in importance as participants review the broader pattern of responses. That iterative structure is particularly useful in a disease area where professional specialties can pull in different directions. A vascular surgeon may value endpoints differently from an emergency physician or a patient who has lived through an ischemic limb event.
The consensus meeting in Phase 3 will finalize the COS. At that stage, the work shifts from collection to decision-making, and the purpose becomes operational rather than exploratory: identify the outcomes that should appear in future studies of acute lower limb ischaemia, regardless of treatment strategy or setting.
Ethics Approval and Practical Research Governance
The protocol already has ethics approval from the Ethics Committee of the Medical University of Innsbruck, EK Nr: 1082/2025, dated 20/05/2025. Additional local approvals will still be required before recruitment begins at participating sites. That layered process is standard for multicenter European research, especially when the study draws on patient interviews and international data collection.
The governance framework matters because a COS project can only work if participation is broad and trustworthy. If the final outcome set is shaped by a narrow group of investigators or a single national system, it will fail to solve the exact problem it was built to address. A durable COS has to be usable across settings with different resources, referral pathways, and treatment preferences.
What This Protocol Could Change for Future ALI Trials
CORE-ALI does not test a drug, device, or surgical technique. Its value lies in shaping the research architecture around acute lower limb ischaemia. That may sound indirect, but in practice it can change which trials are comparable, which meta-analyses are feasible, and which questions guideline panels can answer with confidence.
A shared outcome framework would make it harder for future studies to hide behind selective endpoints. It would also push the field toward outcomes that matter at the bedside, not only in the angiography suite or operating room. When limb-threatening ischemia is at stake, the difference between patency and function, between survival and independence, is not semantic; it determines whether research can truly inform care.
The protocol is registered with the COMET initiative under registration number 3346. Publication of the final core outcome set, along with presentations and society engagement, is planned to support uptake in future clinical trials and professional guidance. The key unresolved issue is not whether ALI needs better outcome reporting; it does. The remaining challenge is whether the field will adopt the final set widely enough to make future evidence more coherent than the literature that exists now.