Clinical trial success depends not only on scientific rigor and patient participation but also on investigator engagement—and that depends heavily on how feasible a study is for the research sites responsible for conducting it.
Protocol complexity has increased substantially in recent years, placing greater pressure on research sites. Between the periods 2009–2012 and 2017–2020, the average number of endpoints per trial increased from 16.6 to 21.1, while the total number of procedures rose from 159.7 to 267.1[1]. This represents roughly a 67% increase in site workload per trial.
For sponsors, this growing site burden can create significant operational challenges. Sites may have less flexibility, which can lead to delayed timelines, slower recruitment, reduced patient outreach, and a higher likelihood of protocol amendments due to delayed feedback or operational bottlenecks.
SubjectWell now helps sponsors understand how their trials compare with others in terms of operational complexity through the Site Burden Index (SBI). When sponsors identify high operational demands early, they can implement measures that reduce site burden—for example, collecting site feedback proactively or running patient recruitment campaigns that prioritize referrals with a higher likelihood of enrollment.
What is a Site Burden Index?
A Site Burden Index evaluates how demanding a clinical trial protocol will be for research sites. It focuses on the operational workload that sites must manage during the study.
Typical components may include:
- Complexity of study visits
- Required procedures and assessments
- Data collection and reporting requirements
- Patient monitoring requirements
- Administrative workload
Together, these elements help sponsors understand how much operational pressure a protocol may place on participating sites.
SubjectWell ‘s Site Burden Index expands this concept by combining operational workload insights with recruitment feasibility analysis.
It forms part of SubjectWell’s broader science-driven feasibility framework, which also includes:
- Patient Burden Index
- Standards of Care assessments
- Site Reach assessments
- Additional feasibility and recruitment tools
Together, these tools help sponsors understand how trial design and recruitment strategies affect:
- Patient willingness to participate
- Site ability to execute the protocol
- Overall recruitment feasibility
This approach allows sponsors to identify potential challenges before recruitment begins and make adjustments that improve trial feasibility. Below are several ways these insights can improve study performance.
Improving recruitment performance
One of the most important benefits of anticipating site burden is improved recruitment outcomes.
When sites must manage complex protocols or heavy administrative workloads, their ability to recruit and manage patients effectively can decline.
The SubjectWell Site Burden Index helps sponsors benchmark their trial with respect to operational workload, ultimately identifying operational factors that may slow site operations and associated patient recruitment. Sponsors can then adjust protocol design, visit schedules, or operational support to allow sites to focus more effectively on patient enrollment.
If the protocol has already been finalized, recognizing a high site burden can still trigger counterbalancing measures. For example, sponsors may prioritize highly pre-qualified patient referrals rather than sending large numbers of potential participants who ultimately fail eligibility criteria. This reduces administrative and screening workload for sites.
The result is often faster recruitment and stronger site performance.
Accelerating study startup
Sites are more likely to participate in studies that they can manage operationally well. When a protocol appears overly complex or resource-intensive, sites may decline participation or delay activation.
Using the SubjectWell Site Burden Index during feasibility assessments helps sponsors align study requirements with site capabilities.
This alignment can lead to:
Faster site activation
Stronger investigator engagement
Improved startup timelines
Reducing protocol amendments
Protocol amendments remain one of the most common and costly challenges in clinical trials. Protocol amendments arise for many reasons, but some occur when the operational burden placed on research sites becomes clearer during study execution.
The SubjectWell Site Burden Index helps sponsors identify potential complexity issues earlier—either during protocol design or before recruitment begins. Sponsors can then account for operational bottlenecks during site onboarding and study planning.
Addressing these issues early reduces the likelihood of mid-study protocol changes, saving both time and resources.
Strengthening site relationships
Research sites play a critical role in clinical development, and sponsors increasingly compete for the attention of experienced investigators and coordinators.
Studies that place excessive operational demands on sites can strain these relationships. In contrast, protocols designed with site feasibility in mind demonstrate a sponsor’s commitment to operational collaboration.
By identifying and addressing operational bottlenecks, sponsor–site and CRO–site relationships can be strengthened through proactive, solution-focused communication and actions taken.
Using the SubjectWell Site Burden Index, sponsors can design trials that respect site capacity and workflow while proactively building long-term partnerships with the clinical research community.
Supporting smarter decisions during the trial
By quantifying operational complexity and site workload, sponsors can make informed decisions that improve both feasibility and performance throughout the trial.
When combined with SubjectWell’s Patient Burden Index and Standards of Care analysis, sponsors gain a comprehensive understanding of how trial design influences both patient participation and site execution.
A better path forward for clinical trials
Clinical trials succeed when patients, sites, and sponsors are aligned.
Tools such as the SubjectWell Site Burden Index help sponsors design studies that are not only scientifically rigorous but also practical for sites to execute and attractive for patients to join.
By understanding and managing site burden early in the trial design process, sponsors can accelerate recruitment, strengthen site engagement, and ultimately bring new therapies to patients faster.
Source
[1] Getz K. et al., Protocol Design and Performance Benchmarks by Phase and by Oncology and Rare Disease Subgroups, Therapeutic Innovation & Regulatory Science (2023) 57:49–56.
