Comparing Turnaround Times Between Central and Local Labs: Regulatory Best Practices

Introduction: The Critical Role of Turnaround Time (TAT) in Clinical Trials

Turnaround time (TAT) for laboratory test results plays a significant role in maintaining trial timelines, ensuring subject safety, and meeting regulatory expectations. Whether dealing with pharmacokinetic endpoints, safety labs, or biomarker readouts, delays in lab data can compromise protocol compliance and data integrity. FDA and EMA inspections frequently highlight TAT discrepancies as audit findings, especially in trials involving multiple sites with varied lab models.

This article explores the operational and regulatory implications of lab TAT. We compare local versus central lab performance and provide insights into how sponsors and CROs can develop TAT metrics, SOPs, and CAPA systems to ensure compliance. The comparison is grounded in real-world examples, global audit trends, and published benchmarks.

Defining Turnaround Time in the Regulatory Context

Turnaround time is typically defined as the duration from sample collection to final result reporting. However, regulators expect TAT to also consider:

• Sample shipment time (collection to lab receipt)
• Sample accessioning time (receipt to data entry)
• Analysis time (data entry to result release)
• Result availability to site personnel and sponsor

Agencies such as the FDA expect TAT to align with the protocol’s safety and efficacy data review timelines. For example, if a protocol mandates SAE evaluation within 48 hours, lab results must support that obligation.

Key TAT Differences Between Central and Local Labs

Central labs offer standardized reporting formats and integrated result delivery, but they often introduce logistical delays due to cross-border shipments. Local labs, conversely, offer speed but vary in equipment calibration, methodology, and reference range documentation.

Global Audit Findings: Delayed Reporting and Risk to Patient Safety

In 2021, an FDA inspection cited a sponsor for failing to act on delayed potassium test results from a local lab, which led to protocol violations for a cardiac safety study. Similarly, a 2022 EMA inspection identified a delay of 5 days in reporting elevated liver enzymes from a central lab due to customs clearance backlogs. These findings highlight the importance of:

• Predefined TAT windows documented in SOPs
• Real-time sample tracking and alerts
• Contingency planning for shipment delays
• Pre-study logistics audits for central labs

Protocol-Driven TAT Targets and CAPA Expectations

Regulatory inspectors expect TAT thresholds to be protocol-driven. These thresholds must be documented and validated during study startup. Deviations from TAT targets should be recorded and analyzed.

Example CAPA actions:

• Root cause analysis of delayed lab report submissions
• Replacement of courier provider for central lab shipments
• Re-training of site personnel on sample packaging and dispatch
• Redesign of lab alert escalation SOPs

Technology Enablers: Automated Alerts and Lab Dashboards

Modern EDC platforms integrate lab portals that provide real-time dashboards for sample receipt, processing, and result upload. These platforms can:

• Trigger alerts for overdue samples or delayed reports
• Provide daily TAT snapshots by site, region, or lab
• Enable dynamic TAT thresholds based on test type (e.g., urgent vs. routine)
• Audit trails for lab result access by investigators

Sponsors are encouraged to include TAT performance in routine vendor oversight reviews and investigator site reports.

Real-World Case Study: Hybrid Lab Strategy in a Global Oncology Trial

A sponsor conducting a Phase 3 oncology trial across 16 countries adopted a hybrid lab strategy: local labs for safety labs and a central lab for biomarker analysis. Initial delays in central lab reporting prompted a revised shipment SOP, which reduced TAT from 5 days to 48 hours.

Benefits realized:

• Reduced data query rates by 35%
• Shortened SAE review cycles
• Favorable EMA inspection outcome with zero major findings on lab data flow

For more regulatory examples involving lab strategies in oncology, see Japan’s RCT Portal.

Conclusion: Building Inspection-Ready TAT Frameworks

Whether using local or central labs, sponsors must establish TAT frameworks that align with the protocol, support subject safety, and comply with GCP expectations. Documentation of every step—from collection to result delivery—must be traceable, auditable, and routinely reviewed. As regulators increasingly focus on lab-linked deviations and delays, proactive TAT planning becomes critical for inspection readiness.

Central labs offer the benefit of standardization but must be balanced against potential logistics-related delays. Local labs offer speed but introduce variability. The best lab model depends on the study design, geographical spread, test complexity, and regulatory risk appetite.