Anonymising a substance misuse file means removing data that names the person. The common-law duty of confidence and UK GDPR Art. 9 protect this care with strict limits on re-disclosure. anonym.plus runs on your own device, and the text stays usable after the swap. Where a service wants to study patterns across records without going back to each person for consent, the route in practice is either full anonymisation or a specific support under s.251 of the NHS Act 2006, overseen by the Health Research Authority's Confidentiality Advisory Group (CAG) — anonym.plus is built for the first path.
When this applies
An NHS Trust's community drug and alcohol team wants to study treatment trends across its caseload. The raw files name people, dates, and referral sources — each detail must be hidden before any analysis, since no s.251 support has been sought for this project.
How anonym.plus handles it
- Open the file in anonym.plus on your own device.
- Local OCR reads scanned referral forms too.
- It flags names, dates, and referral sources.
- Review each flag and protect clinical terms.
- Replace each tag with a label, or remove it.
- Save the clean output. The source never leaves your machine.
What you need to provide
- The file (PDF, DOCX, TXT, or scan).
- An operator: Replace, Redact, or Mask.
- Optional: a key map for re-linking.
Patient data entity types detected
| Category | anonym.plus entity type | Example |
|---|---|---|
| Person | PERSON | Marcus Hale → [CLIENT_1] |
| Admit date | DATE_TIME | Admitted 19/02/2026 → [DATE] |
| Referrer | ORGANIZATION | Northside Magistrates’ Court → [REFERRER] |
| Phone | PHONE_NUMBER | +44 7911 200144 → [PHONE] |
| NHS number | NHS_NUMBER | NHS 321 654 9870 → [NHS_NO] |
| Record ID | MEDICAL_RECORD_NUMBER | Chart 33841 → [MRN] |
Compliance achieved
- Removes identifiers in substance misuse data under the common-law duty of confidence & UK GDPR Art. 9.
- Studying patterns without a NHS Act 2006 s.251 support (Confidentiality Advisory Group approval) means the data must be genuinely anonymised first — that is the standard this tool targets.
- Offline by design, so no cloud processor agreement is needed.
- Source files stay sealed with AES-256-GCM.
- Assessed against ICO Anonymisation Code / UK GDPR Recital 26.
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Limitations & cautions
The common-law duty of confidence limits how substance misuse data may flow to third parties. The tool strips named identifiers. You still control who receives the output and confirm no rare detail can trace it back to one client.
Frequently asked questions
Does UK law cover all substance misuse care?
The common-law duty of confidence applies to all NHS and private clinical records, whether care is delivered by an NHS Trust community team or an independent clinic. UK GDPR Art. 9 adds a special-category layer for health data, so treat every substance misuse file as highly sensitive under both frameworks.
Can I keep a way to re-link cases?
Yes, with care. Save the key map separately and away from the shared copy, so a reader with the de-identified export alone cannot reverse the swap or trace a row back to a named client.
Could the team apply for s.251 support instead of anonymising?
In principle, yes — a trust can seek Confidentiality Advisory Group approval under NHS Act 2006 s.251 to use identifiable data for an approved study without individual consent. That is a separate, formal application process; anonym.plus instead lets a team avoid needing it at all by removing identifiers first.