Development and validation of a brief screening tool for over-the-counter codeine dependence

Low-dose codeine is sold without a prescription in countries like the UK, Ireland, and South Africa. Due to misuse concerns, exploring pharmacy screening tools to identify those at risk and needing additional support is vital.

The study aims to develop and validate a brief screening tool that assesses the risk of codeine dependence with language appropriate for routine use in community pharmacies.

Scale development and validation occurred over two studies. In Study 1, scale item generation was based on structured analyses of psychosocial and pharmacy variables from frequent over-the-counter codeine consumers (N = 795). CFA was used to assess the cohesiveness of the resultant four-item Codeine Dependence Scale (CDS). ROC analyses were used to assess the performance of the CDS against risk cases identified by the Severity of Dependence Scale; identifying an optimal cut-off value of ≥2 as representing individuals at risk of codeine dependence. In Study 2, this CDS threshold was assessed against positive DSM-5 Opioid Use Disorder (OUD) cases related to codeine use assessed using the AUDADIS-IV.

With a cut-off score of ≥2, the CDS has sensitivity and specificity of 76% and 48%, respectively, against a DSM-5 codeine-related OUD diagnosis using the AUDADIS-IV. For identification of any codeine-related OUD (as measured by the AUDADIS-IV) 15 months after baseline, the CDS achieved an overall correct classification rate of 52%; 72% for positive cases.

The CDS exhibits reasonable cross-sectional and longitudinal sensitivity but low specificity, partly due to its brevity. However, the inclusive nature of the CDS is not a negative for application as a screening tool in a pharmacy setting as individual CDS items represent critical conversation points with a pharmacist, regardless of the screening outcome. The non-confronting nature of CDS items make the scale a viable option for pharmacy-based SBI in countries where codeine remains OTC.