Defined daily doses (DDD) do not accurately reflect opioid doses used in contemporary chronic pain treatment

Objective: To assess how well the defined daily dose (DDD) metric reflects opioid utilisation among chronic non-cancer pain patients.

Design: Descriptive, cross-sectional study, utilising a 7-day medication diary.

Setting: Community-based treatment settings, Australia.

Subjects: A sample of 1101 people prescribed opioids for chronic non-cancer pain.

Methods: Opioid dose data was collected via a self-completed 7-day medication diary capturing names, strengths and doses of each medication taken in the past week. Median daily dose was calculated for each opioid. Comparisons were made to the World Health Organization’s (WHO) DDD metric.

Results: WHO DDDs ranged from 0.6 to 7.1 times the median opioid doses used by the sample. For transdermal fentanyl and oral hydromorphone, the median dose was comparable with the DDD. The DDD for methadone was 0.6 times lower than the median doses used by this sample of chronic pain patients. In contrast, the DDD for oxycodone and transdermal buprenorphine, the most commonly used strong opioids for chronic pain in Australia, was two to seven times higher than actual doses used.

Conclusions: For many opioids, there are key differences between the actual doses used in clinical practice and the WHO’s DDDs. The interpretation of opioid utilisation studies using population-level DDDs may be limited, and a recalibration of the DDD for many opioids or the reporting of opioid utilisation in oral morphine equivalent doses is recommended.