Healthcare APIs have made the data exchange much faster and smoother. However, one issue still remains: APIs were not built for large data transfer; they were built for single-patient access.

Moreover, the standardized FHIR R4 APIs work well for viewing patient records or connecting clinical apps. But when healthcare organizations try to scale it for population health data extraction or reporting, it quickly becomes inefficient.

Because extracting data for thousands of patients one by one leads to repetitive API calls, operational strain, and performance bottlenecks. These requests follow synchronously, leading to slow system responses and being resource-intensive at scale.

Most importantly, with healthcare shifting towards value-based care models and data-driven decision-making, analyzing population health data is becoming essential. At the same time, CMS (Centers for Medicare & Medicaid Services) programs and regulations, such as the 21st Century Cures Act, are also pushing for accessible, standardized data. However, exporting patient data at scale is still a major gap.

And this is where bulk FHIR data export comes into the picture to close this gap.

Rather than sending repeated synchronous API calls for individual patient records, FHIR bulk APIs use an asynchronous, system-level approach to extract large volumes of population health data efficiently.

This enables healthcare organizations to move from fragmented data access to scalable, analytics-ready data pipelines. 

In this guide, we will break down how the FHIR bulk API works and how to implement bulk FHIR data export without impacting FHIR interoperability and slowing down operations.

What is Bulk FHIR Data Export?

When it comes to the bulk FHIR data export, it helps healthcare organizations transfer large healthcare data asynchronously across multiple patients from EHR or data sources using standardized FHIR-based APIs.

This ability has a unique operation called $export, which allows providers or clients to request all patient data stored in EHR, data of a particular patient group, or an individual patient’s full datasets.

With this function, healthcare organizations can bulk export health data at three levels: system, group, and patient-level. At the system-level, all data from EHR is extracted, whereas group-level export transfers data from specific groups, and patient-level export extracts complete data for one patient.

To give you an example of these requests, here are three samples: GET/$export, GET/Group/$export, and GET/Patient/$export. 

What makes the bulk export different from RESTful APIs is the asynchronous data extraction model. This means that when the export request is sent, it works in the background without disrupting ongoing operations or any new tasks.

This eliminates the bottlenecks of RESTful APIs and keeps performance stable without any timeouts, and efficiently scales organizations for exchanging large amounts of health data. More importantly, the bulk FHIR APIs export data in NDJSON (Newline Delimited JSON), making large file processing efficient as each line is one resource rather than acting as a single resource package.

The biggest advantage of this format is that healthcare teams don’t have to wait for the download to complete, as they can start working as the data is being downloaded. With this, analytics data pipelines are much faster and more efficient as data becomes available the moment it is exchanged.

In short, bulk FHIR APIs transform FHIR from just an integration standard to a data infrastructure layer. However, bulk FHIR does not replace RESTful APIs because, for real-time access, FHIR APIs are the best choice.

The Architecture of Bulk FHIR vs RESTful API for Large Datasets

One of the most common questions that we get from clients is why not use RESTful APIs and implement bulk FHIR. What is the difference between bulk FHIR vs RESTful API for large datasets? 

Well, the main difference between these two is that REST APIs are designed for real-time patient-level interactions. Whereas FHIR bulk APIs are built to extract large-scale data across patient populations.

Here is a table that explains the difference more clearly:

Moreover, REST APIs follow a synchronous model, which means another request does not begin until the first is not completed. If used for large data exports, it leads to latency as each request is sent individually, with chances of impacting clinical workflows or operations with repeated calls and pagination.

On the other hand, the bulk FHIE APIs work on an asynchronous model where a single $export request triggers health data export in the background, without blocking clinical workflows or other operations. 

Another advantage of bulk FHIR is that the output is delivered in NDJSON files, which can be processed simultaneously and integrated directly into data pipelines. This is completely opposite of REST APIs, which use JSON format, bundling entire data in a single file, needing the entire file download to use the data.

Use Cases: Extracting Population Health Data from EHR Systems

It is much easier to understand the value of bulk FHIR data exports when explained through the common use cases. Because, for a clinician or healthcare CTO, it is easier to visualize the daily scenarios, rather than understanding theoretical knowledge.

One of the primary use cases for bulk data export is population health analytics. With bulk FHIR APIs, clinicians can easily export large datasets to identify trends, monitor chronic conditions, and analyze care gaps across patient groups. With this data available all at once, it becomes efficient to optimize care plans and improve patient outcomes of population health.

Another key use case is risk stratification and predictive modeling. When all patient data for a particular region or patient group is available, it becomes easier for analytical tools to predict hospitalizations, disease outbreaks, and readmission risks, making delivering proactive care possible.

Then the next use case is payer-provider exchange. With bulk FHIR data export, providers can share complete patient records with payers, including parameters such as quality measurement, and get reimbursed under CMS VBC-based programs.

Most importantly, the bulk FHIR helps healthcare organizations maintain regulatory and quality reporting. The organizations are required to submit complete reports on patient improvements for programs such as MIPS. With bulk data exchange, they can extract standardized data without manual aggregation.

Step-by-Step: How to Implement Bulk FHIR Data Export

While implementing bulk FHIR data export, it is important to set up a reliable data pipeline, not just add new APIs.

The first step in the implementation process is to initiate an $export request, as this is the core of bulk health data exchange. This request works across three different levels: system, group, or patient-level. Most of the time, group-level requests are used by organizations to extract data on specific groups, such as diabetic patients or Medicare patients.

After the request is sent, the data is not returned immediately; it shows a status endpoint with Content-Location, indicating the job is being performed. For instance, the server may show HTTP 202 Accepted, Content-Location: https://api.server.com/export-status/abc123. This request is performed in the background asynchronously, making it easier to transfer data without hindering the system performance and clinical workflows. 

Then the next step is to monitor the endpoint and poll it to know the job status. Meaning, you can send repeated requests to know the status of a job, for example, GET/export-status/abc123. When the request is completed, the file is returned in NDJSON format and is properly organized by resource types such as Patient, Observation, or Condition.

The last step of this process is that the downloaded data is stored in a secure location, including data lakes or warehouses. This is where the data is used for analysis by analytical tools, transforming data into actionable insights.

However, if you want to scale effectively, it is important to ensure that data is handled securely and compliantly with end-to-end encryption, role-based access control, and audit-ready data pipelines.

Security & Access Control for Bulk Transfers

With bulk EHR APIs, exporting large volumes of health data becomes efficient, but it also increases the attack surface. This is why it is essential to embed security and access controls in the data pipelines, not just at the endpoints.

The first security measure is to use backend service authorization for secure system-to-system communication. Unlike traditional FHIR APIs, which work on user-based access, bulk FHIR OAuth 2.0 is used to ensure that only trusted applications are able to initiate an $export request with authenticated client credentials.

Another safeguard against cyber threats is to restrict data access to patient groups and not allow system-level access. This enables least privilege access and reduces unnecessary exposure of sensitive PHI.

More importantly, the data pipelines must be secured with end-to-end encryption to prevent breaches in transit or at rest. For encryption, organizations typically use HTTPS along with TLS protocols. This ensures that PHI remains secure during transmission.

Beyond transmission, the secure handling of exported data is equally important. Bulk FHIR outputs are often stored as files, which introduces new risks; that’s why organizations must ensure:

• Secure, HIPAA-compliant storage environments.
• Time-limited access to download links.
• Strong access controls and authentication.
• Audit logging to track data access and usage.

By implementing these practices, healthcare organizations can also meet requirements from organizations such as the Centers for Medicare and Medicaid Services, especially for the value-based care model and data sharing.

Challenges & Best Practices in Bulk FHIR Implementation

Although bulk FHIR data enables scalable healthcare data export, there are several challenges that organizations need to address effectively. 

One of the biggest challenges is to manage large data volumes as the files can be from anywhere between GBs to TBs, as they have multiple resource types. To handle the required storage, the best solution is to use scalable storage solutions, sort data logically by date or resource, and compress files for storage optimization.

Then there is an issue of handling asynchronous job failures and retries. With the data export running in the background, there are chances of failure due to timeouts, network issues, or reaching system limits. To manage this properly, organizations need to implement retry mechanisms, job status tracking, and ensure idempotent requests for reliable data exports.

The third challenge is to maintain data consistency while extracting population health data from EHR. Because the data export is a long process, there are chances of changes in the data or organizations getting incomplete data. That’s why it is important to use incremental exports with parameters such as _since, which helps ensure that only updated data is extracted, improving accuracy and efficiency.

Additionally, relying on full exports can strain systems and increase costs. Best practices are to build optimized data pipelines that support incremental updates, parallel processing, and scheduled jobs.

Frequently Asked Questions