Before a sponsor commits to a clinical trial protocol, it has to answer a question that comes before “which sites should run this”: can this protocol, as designed, realistically be conducted at all? Feasibility assessment is the structured evaluation that answers that question — reviewing the target patient population, the protocol’s operational complexity, alignment with standard of care, the competing-trial landscape, and regulatory pathway before the sponsor commits resources to protocol finalization, country selection, and site selection.
Feasibility assessment and site selection are often discussed together because both use the word “feasibility” and both involve a questionnaire, but they answer different questions at different points in the trial lifecycle. Feasibility assessment asks whether the protocol itself is executable — is there a large enough eligible patient population anywhere, is the visit schedule realistic, does the comparator arm reflect real-world practice. Site selection comes after that question is answered and asks a narrower one: given that the trial can be run, which specific investigative sites should run it. A site-level feasibility questionnaire, the kind covered on the site selection page, is one input into the broader assessment described here, not a substitute for it.
Where feasibility assessment sits in the trial lifecycle
Feasibility assessment typically begins once a protocol synopsis or draft protocol exists — after the core scientific and statistical design decisions covered in protocol design have been made, but before the protocol is finalized, before IRB or ethics submission, and before country and site selection begins in earnest. Findings from a feasibility assessment routinely feed back into protocol design: an eligibility criterion that turns out to exclude most of the available patient population, or a visit schedule judged too burdensome by prospective investigators, is more easily amended at this stage than after sites have already been contracted and initiated.
Published clinical-operations literature on the topic distinguishes study-level (or program-level) feasibility — the assessment covered on this page, conducted by a global study team or feasibility function before site outreach begins — from the site-level feasibility gathered later through individual site questionnaires as part of site selection. The two are sequential and complementary: study-level feasibility determines roughly how many countries and sites a protocol will need and whether the protocol design itself needs to change; site-level feasibility then determines which specific sites within those countries are qualified to deliver it.
What a feasibility assessment evaluates
Epidemiological and patient population analysis
The starting point is disease prevalence and incidence in the target population, using registries, published epidemiological literature, claims data, or electronic health record (EHR) queries rather than investigator impression alone. The analysis goes beyond raw prevalence to test the protocol’s actual eligibility criteria against that population: how the disease stage, biomarker, or prior-treatment requirements the protocol specifies narrow the theoretically eligible population down to a realistically enrollable one, and in which countries or regions that population is concentrated. A protocol with a rare biomarker requirement or a narrow prior-therapy window can look feasible on paper against general disease prevalence and still fail in practice once the actual inclusion/exclusion criteria are applied.
Protocol design complexity
Assessors evaluate the operational burden the protocol places on sites and participants: the number and frequency of study visits, the number and invasiveness of required procedures (imaging, biopsies, specialized labs), the length and complexity of the informed consent process, and how many of those procedures fall outside standard-of-care practice at a typical site. Higher protocol complexity is associated with slower site activation, lower participant retention, and higher screen-failure and dropout rates — all of which a feasibility assessment tries to surface and, where possible, correct through protocol amendment before the design is locked.
Standard-of-care alignment
A protocol’s background therapy, comparator arm, and permitted concomitant medications need to reflect what clinicians in the target countries actually prescribe. Where a protocol’s comparator or washout requirements diverge meaningfully from local standard of care, investigators may be reluctant to enroll patients (since doing so could mean withholding or delaying care they would otherwise provide), ethics committees may raise it during review, and eligible patients may decline to participate. Feasibility assessment checks this alignment early, market by market, rather than discovering the mismatch after sites are already contracted.
Competing-trial and competitive landscape review
This is a broader, region- or country-level version of the competing-studies check that also appears on individual site questionnaires during site selection. At the feasibility stage, the review looks at the overall landscape of trials recruiting the same or an overlapping patient population — searching registries such as ClinicalTrials.gov and other WHO ICTRP primary registries for actively recruiting studies in the same indication — to judge whether the target countries and regions have enough uncommitted eligible patients to support this trial alongside everything already competing for the same population.
Regulatory and administrative feasibility
Assessors review the expected regulatory approval pathway and timeline in each candidate country, including any protocol translation requirements, import/export restrictions on biological samples or investigational product, and country-specific ethics committee or competent-authority review timelines. This determines not just whether a country can support the trial in principle but how long it will realistically take before enrollment can start there.
Site and country capacity estimate
Combining the analyses above, the feasibility assessment produces a working estimate of how many countries and how many sites the protocol will likely need to hit its enrollment target within the planned timeline. That estimate — not a final site list — is the direct output that hands off to site selection, where individual candidate sites within the chosen countries are identified, sent feasibility questionnaires, and evaluated on their own capacity, staff, infrastructure, and track record.
Who conducts feasibility assessment
For sponsor-run trials, a global or regional study team — often including clinical operations, medical/therapeutic-area leads, biostatistics, and regulatory affairs input — typically owns the study-level assessment. Where a CRO is engaged, feasibility work is commonly split: the CRO’s country and regional offices contribute local epidemiological, regulatory, and competitive-landscape input, while the sponsor’s global study team retains responsibility for the overall go/no-go and protocol-amendment decisions. A common practical step at this stage is consulting a small number of prospective investigators or key opinion leaders directly — not yet as a formal site feasibility questionnaire, but as an early sense check on whether the protocol as drafted is one they would realistically be able to execute and enroll patients into.
Outputs and what happens next
A feasibility assessment typically ends in one of three outcomes: the protocol proceeds largely as designed, with the assessment mainly confirming country and site count assumptions; the protocol is amended — a loosened eligibility criterion, a reduced visit schedule, an adjusted comparator arm — based on what the assessment found, before it is finalized; or, less commonly, the assessment surfaces a fundamental mismatch between the protocol as designed and the available patient population or competitive landscape, triggering a broader go/no-go review before further investment. Once the protocol and country/site count assumptions are set, the trial moves into site selection, where those assumptions are tested against real candidate sites.
Frequently asked questions
Is feasibility assessment the same thing as a feasibility questionnaire?
No. A feasibility questionnaire is a specific document sent to individual candidate sites during site selection, asking about that site’s patient volume, staff, and infrastructure. Feasibility assessment is the broader, earlier study-level (or program-level) evaluation of whether the protocol itself is executable, conducted before site outreach begins. Site-level questionnaire responses are one input into a later stage of the process, not the same activity.
How early does feasibility assessment happen relative to protocol finalization?
It typically starts once a protocol synopsis or draft protocol exists, so that findings can still influence eligibility criteria, visit schedule, and comparator design before the protocol is locked and submitted for regulatory and ethics review. Running it earlier, while the protocol is still adjustable, is generally more useful than running it after finalization, when changes require a formal amendment.
What data sources are used to estimate the eligible patient population?
Common sources include published epidemiological literature, disease registries, claims databases, electronic health record queries, and the sponsor’s or CRO’s own historical enrollment data from prior trials in the same indication. Sponsors increasingly weight these data-driven sources more heavily than unverified investigator estimates of how many eligible patients they see.
Does every trial go through a formal feasibility assessment?
Practice varies by sponsor size, trial phase, and indication. Large multinational trials in competitive therapeutic areas (oncology, for example) almost always undergo a formal study-level feasibility assessment because the cost of an infeasible design is high. Smaller, single-country, or early-phase studies sometimes fold a lighter version of the same questions into protocol development rather than running it as a separate, formally documented step.
