Introduction

The US Food and Drug Administration’s (FDA) Bioresearch Monitoring (BIMO) program ensures the integrity of clinical trial data and the protection of human subjects in trials supporting applications for US marketing approval.^1,2 Within this program, Good Clinical Practice (GCP) inspections of clinical investigators, sponsors, and contract research organizations (CROs) verify data reliability and compliance with federal regulations.³ The findings from these inspections and the subsequent GCP assessments directly inform the agency’s regulatory decisions. Understanding the trends in how this oversight is deployed, including where inspections are conducted, which therapeutic areas are prioritized, and how the program adapts to global events, is therefore essential for all stakeholders, including sponsors, regulators, and the public.

The FDA selects clinical investigators for inspection using a risk-based approach, considering factors such as enrollment volume, data criticality to regulatory decision-making, and prior compliance history. Similar risk-based approaches guide the selection of sponsors and CROs for inspection. Inspections reflect both the FDA’s risk-based priorities and the geographic distribution and characteristics of clinical investigators chosen by sponsors during trial design and implementation.

Previous comprehensive analyses of FDA GCP inspections have provided valuable insights into inspection scope and geographic distribution through fiscal year (FY) 2018.⁴ This work examined operational details at the clinical trial site level, establishing key metrics such as inspection coverage, duration, and the geographic distribution of clinical trials and inspections.⁴ However, the impact of the COVID-19 public health emergency and major subsequent geopolitical events has raised critical questions about trends in the volume and location of global inspections. While high-level shifts in inspection volume have been reported by McGuire et al, a detailed, granular analysis of the post-pandemic recovery and its geographic and clinical research areas remains lacking.⁵

This study addresses this gap by analyzing FDA GCP inspection patterns from FY2019 to 2024, spanning pre-pandemic, pandemic, and post-pandemic periods. Using the FY2016–2018 baseline established by Ayalew et al.,⁴ we focused on two specific aims: (1) to quantify geographic shifts in inspection distribution from pre-pandemic to post-pandemic periods, and (2) to characterize the evolving landscape of global clinical research across regions and countries. We also describe inspection outcomes across regions and deficiency area distributions between US and non-US inspections.

Methods

This retrospective descriptive study analyzed FDA GCP inspections conducted for marketing applications in the Center for Drug Evaluation and Research (CDER) from FY2019 to 2024. We extracted data from FDA internal databases: Document Archiving, Reporting & Regulatory Tracking System (DARRTS), Compliance Program Information System (COMPLIS), and Enterprise Content Management System (ECMS).

The marketing applications included New Drug Applications (NDAs), Biologics License Applications (BLAs), and Emergency Use Authorizations (EUAs). During the study period, EUAs were primarily submitted under associated Investigational New Drug Applications (INDs) in response to the COVID-19 public health emergency.¹

We identified GCP inspection requests dated between FY2019–2024 through data queries in COMPLIS. The analysis included all requests with at least one completed GCP inspection for marketing applications. We excluded GCP inspection requests if all FDA-conducted GCP inspections were canceled, identified as duplicates or for-cause inspections, or involved Bioavailability (BA) and Bioequivalence (BE) studies.

Geographic and therapeutic area distributions were compared across three periods: pre-pandemic (October 1, 2015–January 29, 2020), during pandemic (January 30, 2020–May 10, 2023), and post-pandemic (May 11, 2023–September 30, 2024).^6,7

Descriptive statistics were generated using JMP 17 and Microsoft Excel. The following variables were extracted for analysis:

• Application-level data: application type (NDA, BLA, or EUA), submission type (original or supplement), review designation (priority or standard), indication and therapeutic area.

• Inspection-level data: establishment type (clinical investigators, sponsors, or CROs), geographic location (US or non-US), duration of assessment, final inspection classification (NAI [No Action Indicated], VAI [Voluntary Action Indicated], or OAI [Official Action Indicated]), and deficiency area (adherence to trial protocol, adequacy of records, monitoring/trial oversight, reporting safety information, informed consent, drug accountability, or Institutional Review Board (IRB) approval).

For regional analyses, all non-US countries were grouped into seven geographic regions: Western Europe (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Netherlands, Portugal, Spain, Sweden, Switzerland, and United Kingdom), Eastern Europe (Belarus, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Georgia, Hungary, Latvia, Lithuania, Poland, Romania, Russia, Serbia, Slovakia, and Ukraine), Asia (China, India, Japan, Philippines, South Korea, Taiwan, Thailand, and Vietnam), North America (excluding US; Canada, Mexico, and Panama), South America (Argentina, Brazil, Chile, and Peru), Middle East (Israel and Turkey), Africa (South Africa), and Pacific (Australia and New Zealand). The percentage of NAI, VAI, and OAI were calculated as the number of inspections with the respective classification out of the total inspections for the region.

Country-level analyses included countries with ≥20 total inspections within the analysis timeframes to ensure adequate sample sizes for meaningful trend analysis.

To assess the impact of the COVID-19 public health emergency, we integrated data from a prior analysis covering FY2016–2018 to enable evaluation across the three pandemic time periods.⁴ Annualized inspection rates (i.e., the total number of inspections in each time period divided by the number of months in that period, multiplied by 12) were calculated to compare inspection trends across these distinct periods. The rate difference and percentage change between the pre- and post-pandemic periods were calculated as follows:

$\begin{array}{l}\text{Inspection rate difference}\hspace{0.17em}\text{=}\hspace{0.17em}\text{post-pandemic annualized rate }\hspace{0.17em}\\ \text{ –}\hspace{0.17em}\text{pre-pandemic annualized rate}\end{array}$

$\begin{array}{cc}\text{Percentage change}& =\frac{\text{inspection rate difference}}{\text{pre-pandemic rate}}\times 100\%\\ & \end{array}$

Results

Discussion

This analysis of 713 FDA GCP inspection requests from FY2019–2024 characterized geographic and therapeutic area patterns spanning pre-, during, and post-pandemic periods. Building upon the established pre-pandemic baseline, which characterized inspection scope and geographic distribution from FY2016 through FY2018, our findings indicate the recovery of GCP inspections after the pandemic was not uniform and appeared to be influenced by regulatory site selection for inspections, therapeutic area priorities, geopolitical events, and sponsor trial location decisions.⁴ We did not re-examine operational metrics such as inspection duration and inspection coverage (including number of trial participants and volume of source documents reviewed), which were hypothesized to remain stable due to the consistent BIMO program framework.^1,2

The increase in US-based inspections to nearly 90% in FY2020 is consistent with international travel restrictions during the COVID-19 public health emergency and aligns with high-level trends reported by McGuire et al.^5,8 During this period, the FDA employed alternative assessment tools, such as RRAs, to maintain regulatory oversight when on-site inspections were not feasible.⁹ The subsequent decline in US proportion indicates resumption of international inspections, though the distribution across regions was heterogeneous.

Asia demonstrated the largest relative increase in post-pandemic inspection rates, driven primarily by South Korea and China (Table 6). This growth was highly concentrated in oncology across the region. All inspections in China and most in South Korea involved oncology trials (Table 5). Notably, China showed an increase in its annualized inspection rate during the pandemic period itself, an exception to the broader pandemic-period slowdown (Table 6).

These patterns coincide with several developments in the region. China’s accession to the International Council for Harmonisation (ICH) in 2017 streamlined pathways for international clinical trials, and the region has experienced growth in domestic biotechnology industries that conduct trials to support both Chinese and US marketing applications.^{10, 11, 12, 13} The region also offers large patient populations and established clinical research infrastructure.¹⁴

Eastern Europe showed an overall decline in post-pandemic inspection rates, with marked heterogeneity across countries (Table 6). Ukraine, which accounted for 3.7% of all non-US inspections from FY2016–2018,⁴ had zero post-pandemic inspections. This cessation coincided with the February 2022 US State Department Level 4 (“Do Not Travel”) advisory and reports of clinical trial disruption.^{15, 16, 17, 18, 19} Several of the countries that border Ukraine also showed declines, including Hungary and Romania. Industry reports from this period describe sponsors relocating trials from the region due to perceived geopolitical risk, operational challenges including staff departures and supply chain disruptions, and travel advisories affecting site access.^16,20,21

While some industry data point to a decline in the region’s share of clinical trials from 2019 to 2024, our data show a 59.1% increase in post-pandemic inspection rates in Poland through FY2024 (Table 6), with inspections during FY2019–2024 distributed across multiple therapeutic areas.²² This growth is consistent with industry reports of Poland as an attractive research hub, noted for its operational stability, European Union (EU) membership, and established infrastructure.^{23, 24, 25, 26} This increase may reflect the completion of previously initiated pivotal trials during the study period and the country’s role in ensuring the continuity of research activities disrupted in Ukraine.^16,27

Bulgaria showed a 220% relative increase in inspection rates (from 2.5 to 8.0 inspections/year), though this represents a smaller absolute change given the low baseline (Table 6). Bulgaria also showed a distinct therapeutic area profile for FY2019–2024, with infectious diseases comprising the highest proportion among countries with ≥20 inspections (Table 5). These included trials for COVID-19, bacterial infections, and fungal infections conducted by multiple sponsors. Industry participants have identified Bulgaria as a key hub for clinical research, valued for its cost-effectiveness and harmonized regulatory environment within the EU.^28,29

The key therapeutic patterns observed in this study, including the global concentration in oncology and regional prominence of infectious diseases, are consistent with broad distributions reported previously.^4,30 Our analysis provides new, regional granularity to these findings. While oncology was the leading category across most regions, its proportion varied substantially. In contrast, Eastern Europe and Africa presented distinct profiles, where infectious diseases were the leading categories (Table 4).

This geographic variation reflects several factors. For oncology, regional differences in cancer incidence, treatment patterns, and availability of treatment-naïve patients influence where sponsors conduct oncology trials. Regulatory requirements may contribute to geographic diversity in oncology development.³¹ Similarly, the concentration of infectious disease inspections in certain regions may reflect regional expertise or temporal clustering of trials for pathogens of global concern, such as COVID-19. More broadly, operational considerations such as enrollment timelines, costs, and infrastructure also influence sponsor trial location strategies.²² FDA risk-based site selection may prioritize high-enrollment sites and those generating critical or complex data.

Final inspection classifications, including cited deficiency areas, reflect the compliance status of the individual inspected establishment and should not be interpreted as an assessment of overall GCP compliance in a given region. The predominance of NAI classifications is consistent with previously published data, suggesting broadly comparable levels of GCP compliance across geographic regions.⁵ Similarly, where deficiencies were observed, rates of nonadherence to trial protocol and inadequacy of records were also consistent with previously published findings.⁵ OAI classifications were too infrequent for meaningful regional comparison. The higher percentage of monitoring/trial oversight deficiencies in US inspections may reflect the concentration of sponsor and CRO inspections domestically, given that these deficiencies are predominantly associated with inspections of these establishments.

Several limitations should be noted. First, the analysis is limited to the FDA’s review-based BIMO inspections for CDER marketing applications and excludes alternative tools like RRAs.⁹ Second, the number of inspections reflects where the FDA conducted oversight, not total trials conducted in each region; geographic trends therefore reflect both FDA site selection and sponsor trial location decisions, which cannot be distinguished with available data. A small number of inspections in South America, Africa, and the Middle East preclude meaningful interpretation of changes in these regions; similarly, small sample sizes in most non-US regions precluded a regional breakdown of deficiency areas. Finally, the observed differences in inspection classifications and deficiency areas should be interpreted with caution, as this descriptive analysis was not designed to evaluate the underlying factors contributing to these differences.

The observed geographic shifts have important implications for the FDA’s global inspection strategies and resource allocation. The substantial regional variation in post-pandemic inspection patterns reflects the dynamic nature of the global clinical trial landscape and the need for flexible regulatory approaches.

Several avenues for future research could build upon these findings, including analysis of the broader geographic distribution of clinical trial sites supporting marketing applications, which would help distinguish trends in sponsor trial location decisions from the FDA’s risk-based site selection for inspection. As the post-pandemic period (May 2023–September 2024) was relatively short, longitudinal analyses extending beyond this period would clarify whether observed patterns represent recovery of temporary disruptions or sustained shifts in global trial conduct. Understanding these evolving patterns is essential for maintaining robust oversight of global clinical trial activities.

Conclusions

This analysis of 713 FDA GCP inspection requests from FY2019–2024 demonstrated substantial shifts in geographic distribution and scope following the COVID-19 pandemic. Post-pandemic inspection rates increased in Asia and decreased in Eastern Europe, with marked heterogeneity at the country level. In aggregate, the inspection classifications and cited deficiency areas were broadly comparable between US and non-US inspections. The observed variation may reflect differences in site selection, site characteristics, or other factors not assessed in this study. Therapeutic area distribution varied substantially by region, with oncology predominating in Asia and infectious diseases in Eastern Europe.

These patterns reflect the complex interplay of the pandemic, geopolitical events, therapeutic area priorities, and sponsor trial location decisions. As the global clinical research landscape continues to evolve, the FDA’s GCP inspection program should maintain adaptive strategies that can respond to shifting geographic and therapeutic priorities while ensuring robust oversight of an increasingly dynamic international trial environment.

Acknowldgements

We would like to thank Yolanda Patague and Loreto-Corazon Lim for recording GCP inspection data. We also thank Lee Pai-Scherf, MD, for recommending the update to the previously published inspection data. We thank David Burrow, PharmD, JD, for his review of the draft manuscript. We thank all FDA inspectors from OII (Office of Bioresearch Monitoring Inspectorate) for the GCP inspections they conducted, and all the GCP Assessment Branch staff for their collaboration with internal and external stakeholders for the GCP review work in support of marketing applications.

Funding Information

No financial support was received for this article’s research, authorship, and/or publication.

Competing Interests

The authors declare no conflicts of interest. The views expressed in this article are the personal views of the authors. They may not be understood or quoted as being made on behalf of or reflecting the FDA’s position with which each author is affiliated.

Author Contributions

JS, KA, and CM conceived the study design. CM was responsible for data collection, quality control, and data verification. CM also conducted the data analysis and generated all tables. CM, JS, and KA drafted the manuscript, and all authors provided critical revisions and intellectual content.

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