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E
Explicit consent
F
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FDPIC (Swiss Federal Data Protection and Information Commissioner)
F
Federated learning
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F
First-in-human (FIH) trial
F
Food and Drug Administration (FDA)
F
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G
General Data Protection Regulation (GDPR)
G
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G
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G
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H
HDS certification (Hébergeur de Données de Santé)
H
Health data access body (HDAB)
H
Health data warehouse (HDW)
H
HHS Office for Civil Rights (OCR)
H
High-risk AI system
H
HIPAA (Health Insurance Portability and Accountability Act)
H
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H
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H
Human subjects protection review board
I
ICH E6(R3)
I
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I
Information Commissioner's Office (ICO)
I
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I
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I
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I
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I
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Joint controllers
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L
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L
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L
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M
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M
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M
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M
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M
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N
Natural history study
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O
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Q
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Q
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Q
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Query (clinical data query)
R
Randomisation and trial supply management (RTSM)
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Term of the Day

Natural history study

A natural history study is a preplanned observational study intended to track the course of a disease over time, identifying demographic, genetic, environmental and other variables that correlate with its development and outcomes in the absence of intervention, or under standard of care. Designs may be retrospective (chart review of existing records) or prospective (longitudinal follow-up of a cohort or registry).

Natural history data is particularly important in rare and paediatric diseases, where randomised placebo-controlled trials may be infeasible or unethical. The FDA (guidance on rare disease natural history studies, 2019) and the EMA accept well-designed natural history studies to define endpoints and biomarkers, identify patient subgroups, estimate sample sizes and, in some cases, serve as external or historical control arms for single-arm trials supporting orphan products.

Because they are non-interventional, natural history studies fall outside the CTR and are governed by national law (for example France's MR-003 or MR-004 reference methodologies) and by the GDPR. They typically involve secondary use of medical records, long-term follow-up, genetic data and small populations in which anonymisation is rarely achievable, so pseudonymisation, a DPIA and a robust research legal basis under Art. 9(2)(j) are essential. Registries maintained by patient organisations or academic consortia raise additional questions of joint controllership and data access governance.

L

Limited data set (HIPAA)

A limited data set under HIPAA is protected health information from which specified direct identifiers have been excluded. It may be used or disclosed for research, public health or healthcare operations under a qualifying data use agreement. It remains protected health information, unlike information properly de-identified under HIPAA.

Key Takeaways

  • Removing names alone does not create a compliant limited data set.
  • The permitted purposes are research, public health and healthcare operations.
  • The recipient needs the required data use agreement, not an assumption that reduced identifiers mean unrestricted use.

How Does It Differ From De-Identification?

ElementMeaning
Limited data setStill protected health information
Required exclusionsSpecified direct identifiers must be removed
De-identified informationMust satisfy a separate HIPAA standard

The HIPAA rule excludes sixteen categories of direct identifiers relating to the individual and relevant relatives, employers or household members. These include names, telephone numbers, email addresses, medical record numbers, biometric identifiers and full-face photographs. The address exclusion permits town or city, state and ZIP code. A data use agreement must define permitted uses and recipients and contain safeguards, including restrictions on identifying or contacting individuals. This is a distinct route from HIPAA’s expert determination and Safe Harbor methods for de-identification.

Primary guidance: HHS HIPAA audit protocol, section 164.514(e); HHS de-identification guidance.

Why It Matters for Data Protection

For a hypothetical outcomes research collaboration, we recommend checking the actual extract against the full regulatory exclusion list, not a shortened project checklist. Document why the recipient needs the retained information and ensure that the agreement matches the research activities. Review narrative fields as well as structured columns. Keep a record of who receives the extract and how onward access is controlled. Where a project also involves another privacy regime, assess that regime separately rather than treating HIPAA status as a universal permission to share.

Frequently Asked Questions

Is a limited data set anonymous?

No. It remains protected health information under HIPAA.

Can city and ZIP code remain?

Yes, the limited-data-set address exclusion specifically permits them.

Can it be used for any business purpose?

No. This route is limited to research, public health and healthcare operations.

Related reading: de identification; protected health information phi.

Explore iliomad’s HIPAA support for your organisation.

Updated: 27 October 2026