An evidence-based approach to assess the use of opioids

Thesis

Background: Since the 1990s, the prescribing of opioids has increased in England and most high-income countries. However, insufficient datasets used in previous research may have underrepresented the extent of the problem.

Aims: To assess global and national use of opioids, drivers of suboptimal use, and consider strategies to prevent opioid-related deaths.

Methods: I conducted two cross-sectional analyses and two retrospective observational studies, using several datasets, including controlled opioid consumption statistics from the International Narcotic Control Board, the Global Essential Medicines Database of 137 national essential medicines lists, sales of over-the-counter products containing codeine, and the Preventable Deaths Database. I performed a synthesis of pharmacological resources and a systematic review of observational studies to explore factors associated with high-dose opioids.

Results: 687 million people (10% of the global population) consumed 89% of the world’s controlled opioids in 2015-17. Countries included a median of 6 opioids (IQR: 5-9; range: 0-19) in national essential medicines lists; morphine (95%), fentanyl (83%), and codeine (69%) were the most common. 31.5 billion units of codeine, costing £2.55 billion, were sold over-the-counter across 31 countries in 2013-19, with 3% and 54% increases respectively. In the UK, 4.75 billion dosage units of codeine in combination with 1711 tonnes of paracetamol and 96 tonnes of ibuprofen, costing £638 million, were purchased over-the-counter in 2013-19. I identified 233 opioid drugs and created the Oxford Catalogue of Opioids (https://www.catalogueofopioids.net/). Five factors were associated with high-dose opioids, including co-prescription of benzodiazepines, depression, Emergency Department visits, unemployment, and being male. There were 176 opioid-related Prevention of Future Deaths reports in 2013-19, with a 262% increase. I created the Preventable Deaths Tracker (https://preventabledeathstracker.net/) and launched the Coroners’ Concerns to Prevent Harms series in BMJ Evidence-Based Medicine.

Conclusions: There are persistent disparities and variations in the use of and access to prescribed and non-prescribed opioids. While opioids can be overused or underused, and can cause fatal and non-fatal harms, they still have a place in modern medicine in the right patient, at the right dosage regimen, and for the right reasons. I have outlined future research to serve patient safety, reduce avoidable harms, and improve evidence-based decision-making in clinical practice and policy.

Authors: Richards, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: essential medicines; Prevent future deaths; primary health care; opiates; narcotics; over-the-counter; opioids; harms; codeine; preventable deaths; pharmacoepidemiology; evidence-based medicine; drug safety; coroners' reports; avoidable harms; epidemiology
• Subjects: Epidemiology; Pharmacoepidemiology; Primary health care; Primary health care--Great Britain; Evidence-based medicine; Epidemiology--Methodology