Clinical trials are designed to
answer critical questions about the safety and effectiveness of new medicines,
but before a trial can generate meaningful evidence, sponsors must overcome
another challenge: making sure the study is operationally feasible. A protocol
may look achievable on paper, yet patient recruitment can prove slower than
expected, sites may lack adequate capacity, investigators may already be
committed to competing studies, or regulatory and operational requirements may
create unexpected delays. These problems can become expensive once a trial is
underway because correcting them often requires changes to sites, recruitment
strategies, timelines, or even the study design.
A study published in Therapeutic
Innovation & Regulatory Science using Tufts Center for the Study of Drug
Development benchmarks found meaningful differences in site activation and
enrollment performance across regions and site types. Tufts data also showed
that, in 2023, only about 71% of global investigative sites enrolled at least
one patient in Phase II and III trials, compared with 86% in 2019. This is
where expert networks can play a valuable role. By connecting sponsors with
experienced clinical investigators, site leaders, clinical operations
professionals, regulatory specialists, and other healthcare experts, expert
networks can help identify potential bottlenecks before they become operational
problems.
Why Clinical Trial Bottlenecks
often Begin Before Recruitment
Clinical trial delays are rarely
caused by a single factor. They can emerge from decisions made during protocol
development, country selection, site selection, patient eligibility planning,
or study start-up. The challenge is that many of these risks are difficult to
identify through historical datasets alone.
A database may show how many
eligible patients exist in a particular geography, but it may not reveal how
many are realistically accessible to participating sites. Similarly, a site may
appear highly qualified based on previous trial experience but have limited
investigator capacity or several competing studies at the time a new trial is
scheduled to begin.
Research examining 2,542 randomized
surgical trials registered on ClinicalTrials.gov found that only 20.4% were
completed within their planned timeframe, while 45.9% reached their
prespecified enrollment target. Among completed trials that experienced delays,
the median delay was 12.2 months. Although the study focused on surgical trials
and should not be generalized to every therapeutic area, its findings
illustrate the consequences of overestimating feasibility during planning. The
earlier these risks are identified, the more opportunities sponsors have to
address them.
Identifying Patient Recruitment
Bottlenecks
Patient recruitment remains one of
the most important areas of clinical trial feasibility. A study may identify a
large disease population and conclude that sufficient participants should be
available. However, the number of people who actually qualify under a specific
protocol can be significantly smaller. Eligibility criteria, prior treatment
history, comorbidities, geographic access, diagnostic requirements, and
willingness to participate can all affect the realistically recruitable
population.
The FDA's recent guidance on
enhancing participation in clinical trials specifically addresses eligibility
criteria, enrollment practices, and trial designs, emphasizing the importance
of designing studies that can enroll representative populations. The guidance
recognizes that factors such as age, location, comorbidities, disabilities, and
disease prevalence can influence participation.
Expert interviews can add another
layer to this assessment. A treating physician can help determine whether the
protocol's target patient profile reflects the patients actually seen in
clinical practice. An investigator can discuss how restrictive eligibility
criteria may affect screening. A site-level expert can explain whether patients
are likely to travel for study visits or whether the frequency of assessments
could discourage participation.
Understanding Competing Clinical
Trials
Competition for eligible patients
is another potential bottleneck. In therapeutic areas with significant research
activity, several sponsors may be targeting similar populations at the same
hospitals or within the same geographic markets. A site that appears attractive
because of its patient volume may therefore face intense competition for
eligible participants.
Public trial registries can help
identify competing studies, but they may not provide a complete picture of how
competition affects recruitment at the site level. Investigators and clinical
research professionals can provide context around which studies are actively
recruiting, how attractive different protocols are to patients, and which
trials are likely to receive priority from clinical teams. This type of insight
can help sponsors evaluate whether a proposed site has genuine recruitment
capacity rather than simply historical patient volume.
Assessing Site Activation Risks
Even after a site has been
selected, activation can become a bottleneck. Contracts, budgets, ethics or
institutional review processes, staff training, technology implementation,
laboratory arrangements, and other start-up activities can affect when a site
becomes operational. Tufts CSDD's recent benchmarking provides an important
signal here.
Its data showed that the average
proportion of investigative sites enrolling at least one patient in Phase II
and III trials was approximately 71% in 2023, down from 86% in 2019. The
decline was particularly notable in APAC, LATAM, and North America. Expert
conversations can help sponsors understand why. Experienced site professionals
may be able to explain common causes of delayed activation, recurring
contracting issues, staffing constraints, or operational requirements that
should be considered during planning.
Building More Representative
Clinical Trials
Feasibility is not only about
enrolling enough participants. Increasingly, sponsors must also consider
whether the trial population adequately represents the patients who may
ultimately use the product. The FDA's 2024 draft guidance on Diversity Action Plans
called for sponsors to establish enrollment goals and strategies for increasing
participation among underrepresented populations in applicable clinical
studies. The agency has emphasized the importance of using appropriate
population data and practical strategies to achieve representative enrollment.
Local investigators, community
healthcare professionals, patient-access specialists, and other experts can
provide insight into whether proposed recruitment locations are capable of
reaching the intended populations. They can also help identify practical
barriers involving travel, referrals, healthcare access, and patient
engagement. Population statistics can establish where potential participants
live. Local experts can help explain whether those patients can realistically
enter the trial.
Using Multiple Experts to
Stress-Test a Trial Strategy
One expert rarely provides the
complete picture. A clinical investigator may understand patient treatment
patterns but have limited visibility into sponsor-level operational
constraints. A CRO professional may understand study execution but not the
nuances of a particular patient population. A regulatory expert may identify
approval risks that neither group would necessarily see.
This is why a multi-perspective
expert strategy can be more useful than relying on a single interview. Sponsors
can compare perspectives and identify areas of agreement or disagreement. If
investigators consistently report that eligibility criteria are too
restrictive, for example, that feedback can prompt a closer review of the
protocol. If several site professionals identify staffing as a concern, the
sponsor can investigate site capacity before finalizing the network.
Turning Expert Insights Into
Pre-Trial Decisions
The value of expert research
ultimately depends on what happens after the interviews. If experts identify
limited patient access in a particular geography, sponsors can reassess site
distribution. If investigators flag protocol complexity, the development team
can examine whether procedures can be simplified. If regulatory specialists
identify potential approval constraints, timelines and country selection can be
reconsidered.
This creates a practical cycle in
which expert research becomes part of the decision-making process rather than a
standalone research exercise. The process can begin with a defined feasibility
question, followed by identification of the professionals best positioned to
answer it. Their perspectives can then be compared against existing data,
assumptions can be challenged, and potential bottlenecks can be prioritized
according to their likely impact.
Why Early Expert Research Matters
The economics of clinical
development make early risk identification particularly important. A bottleneck
discovered before site selection can often be addressed through planning. The
same bottleneck discovered after multiple sites have been activated and
recruitment has begun can require considerably more time and resources to
correct.
This does not mean expert networks
can eliminate clinical trial delays. No research method can guarantee that a
trial will recruit on schedule or avoid operational challenges. Their value
lies elsewhere: expert networks can help sponsors see potential problems
earlier. By combining quantitative feasibility data with firsthand perspectives
from people who understand clinical research in practice, sponsors can develop
a more realistic picture of what execution may look like.
Conclusion: Identify the Bottleneck
Before the Trial Does
Clinical trial bottlenecks rarely
announce themselves at the beginning. They emerge when theoretical assumptions
encounter real-world conditions. A site may have the right credentials but
insufficient capacity. A patient population may look large but prove difficult
to recruit. A protocol may be scientifically rigorous but operationally
burdensome. A market may appear attractive but introduce regulatory or
infrastructure challenges.
Real-world research shows that
enrollment, site activation, trial complexity, and recruitment remain
significant challenges across clinical development. Expert networks provide a
way to bring firsthand industry knowledge into the planning process before these
issues become visible through trial performance.