Chamber and committees

Estimates of the number of people prescribed opioid substitution therapy (OST) in Scotland are published on the Scottish Public Health Observatory website as, in spite of some data quality issues, Public Health Scotland (PHS) deem there to be a public interest in reporting this information. These statistics are published in a way that accurately describes the limitations of these data. Further, these estimates have been subject to external validation which indicates that their accuracy is good and has improved over time.

ISD (now Public Health Scotland) first published estimates of the number of people prescribed methadone for opioid dependence in 2015. The narrative accompanying these statistics states that, in spite of Community Health Index (CHI) capture being below the agreed threshold of reliability for individual-level analysis, these statistics are published due to ongoing public interest. As drug-related deaths have become an issue of growing concern, it is felt that this public interest argument continues to provide a strong reason for publication of statistics relating to prescribing for opioid dependence.

The way in which these statistics are published accurately reports the data quality issues that may affect their reliability. These statistics are published as ‘Management Information’ and the accompanying narrative describes the data quality issues and other appropriate caveats. The estimates are appropriately described as a ‘minimum number’ of people prescribed OST medications. Also, patient age and sex analysis that would typically be included for medications where CHI capture was above the agreed threshold of reliability for individual-level analysis, are not included.

Although the percentage of CHI numbers that were successfully captured from community prescriptions for OST medications in Scotland remains below the agreed threshold of reliability for individual-level analysis, there has been a substantial improvement in the quality of the underlying data over time. For the OST estimates, the CHI capture percentage increased from 64% in 2011-12 to 81% in 2021-22. As the information on ScotPHO in relation to prescribing for opioid dependence has developed, PHS have taken steps to understand how CHI capture affects the reliability of these estimates. Prior to releasing the first annual estimate of numbers of people on OST in March 2022, PHS held discussions about estimation methodologies with NHS Board prescribing leads and worked with them to agree a suitable way forward.

An analysis (also published on ScotPHO ) comparing estimates of the numbers of people on OST generated from NHS Board systems with the estimates produced by PHS shows that there was less than 1% difference between the 2020-21 total derived from local systems (29,588) and the PHS estimate (29,416). PHS continues to work with NHS Boards to improve the reliability of data on OST and any associated analyses.