Opioid-related deaths in past decade 55% higher than recorded

Deaths following opioid use in England and Wales have nearly doubled in the last decade, with 22.9 deaths per million people in 2012, and 43.8 deaths per million people in 2023. But the true number is likely higher because of a constraint of the data provided by coroners to the Office for National Statistics (ONS).

In a study published today in the International Journal of Drug Policy, researchers from the Faculty of Life Sciences & Medicine used data from coroners’ reports submitted to the National Program on Substance Use Mortality data (NPSUM) based at the university to triangulate and better estimate the number of opioid-related deaths.

While the total number of drug deaths is accurate, the count for deaths due to specific substances is limited by the fact the ONS does not have access to post-mortem reports or toxicology results.

Instead, the accuracy of figures depends on the information provided by the coroner on the death certificate. If that is missing information, such as when an individual dies from using multiple drugs at the same time—known as polydrug use—and it is recorded with ambiguous terms such as “multidrug overdose,” the ONS cannot determine the individual substances involved. As a result of this incomplete information, the ONS warns that figures for drug misuse for specific substances are underestimates.

Researchers found the number of unaccounted deaths has grown in the past decade. The ONS recorded 574 heroin/morphine-related deaths in 2011 but by using NPSUM data, researchers found there were a likely 239 further unaccounted deaths—underestimated by 29%. This gap grew to 34% by 2022, with the ONS recording 1,264 deaths but the researchers projected there were 1,980.

She added, “The increase in users taking more than one drug increases the likelihood of accidental overdose and also adds to the reporting problem. We need to alert coroners to the impact that not naming specific drugs as the cause of death has on the planning and funding of public health policies.”

The rate of underestimation in the recorded data has increased over time for heroin/morphine, methadone, tramadol, dihydrocodeine and fentanyl.

The authors say it is likely ONS data reporting deaths due to other specified substances—such as cocaine—are likely underestimated too. Researchers at King’s are extending this study to provide estimates for the number of deaths due to other specified substances that ONS provides.