PHS FOI 2025-002312
- Date of request
- 19 December 2025
- Date of response
- 19 January 2026
- FOI request ID
- PHS FOI 2025-002312
- Drugs
Request
‘I am requesting information relating to the completeness, reliability, and known limitations of Opioid Substitution Therapy (OST) prescribing data used by Public Health Scotland (PHS), including data derived from the Prescribing Information System (PIS) and Hospital Medicines Utilisation Database (HMUD).
Please provide the following information:
For each financial year from 2015/16 to the most recent year available:
The percentage of OST prescriptions with a valid CHI number recorded.
The percentage without a valid CHI number.
Any internal thresholds or criteria used by PHS to determine when OST data are considered reliable for reporting purposes.
Any internal reports, audits, reviews, risk logs, or briefing papers (including draft documents) produced since 2015 that:
Refer to missing, incomplete, or unreliable CHI capture in OST prescribing data.
Discuss undercounting, data suppression, or uncertainty in published OST patient estimates.
Any correspondence (emails, memos, briefing notes) between PHS and:
Scottish Government
NHS Boards
Alcohol and Drug Partnerships (ADPs)
since 2015 that discusses:
Data quality concerns relating to OST prescribing
Missing CHI numbers
Limitations of OST patient estimates
A list of methodological changes made since 2015 to how PHS estimates the number of people prescribed OST, including the rationale for each change.
Copies of any Freedom of Information requests and responses received by PHS since 2015 that relate specifically to:
OST data completeness
Missing CHI numbers
Reliability or accuracy of OST prescribing statistics
If any of the requested information is held but considered exempt, please specify the exemption relied upon and provide the information in redacted form where possible.
I would prefer the information in electronic format.’