About 1% of US opioid providers account for nearly half of all opioid doses

The findings suggest that efforts to promote careful prescribing should focus on these top providers and their patients, rather than imposing rigid thresholds on all providers, say the researchers.

Opioid prescribing remains far higher in the US than in other countries, despite efforts to reduce inappropriate prescribing. Previous studies have noted that opioid prescribing in the US is skewed, but were limited to narrow samples of providers or patients over shorter periods.

In an attempt to fill these gaps, a team of researchers set out to examine the distribution and patterns of opioid prescribing in the United States.

Their findings are based on prescribing data from a large, national private insurance provider covering more than 60 million individuals from 2003 to 2017 across all 50 US states and Washington DC.

Using this information, they identified whether opioids are roughly equally prescribed across US medical providers or disproportionately prescribed by a small subset of providers. They also examined how prescribing patterns have changed over time and relationships between top prescribers and top receiving patients.

Between 2003 and 2017, an average of 8.2 billion standard doses of opioids in morphine milligram equivalents (MMEs) were prescribed by 669,495 providers to 3.9 million patients a year.

In 2017, the top 1% of providers accounted for 49% of all opioid doses and 27% of all opioid prescriptions. In absolute terms, the top 1% of providers prescribed an average of 748,000 MMEs -- nearly 1,000 times more than the middle 1%.

At least half of all providers in the top 1% in one year were also in the top 1% in subsequent years.

And while guidelines recommend that new opioid prescriptions for treating acute pain should comprise a dose of less than 50 MMEs a day and a duration of fewer than seven days, the results show that more than two fifths (42% to 49%) of all prescriptions written by the top 1% of providers were for more than 50 MMEs a day and over four fifths (81% to 98%) were for longer than seven days.

In contrast, prescriptions written by the bottom 99% of providers were below these thresholds, with 86% of prescriptions for less than 50 MMEs a day and 71% for fewer than seven days.

Providers prescribing high amounts of opioids and patients receiving high amounts of opioids persisted over time, suggesting that these providers have established relationships with their patients over multiple years.

This is an observational study, so can't establish cause, and the researchers note that the data did not allow them to assess the clinical appropriateness of any opioid or benzodiazepine prescription, and might not be fully generalisable to the whole of the US.

They also point out that specialties with additional training in clinically appropriate opioid prescribing -- for example, anesthesiology or pain management and rehabilitation -- are overrepresented in the top centile of opioid prescribing providers.

Nevertheless, they say these data covered a patient population closely representative of the age and sex distribution of the general US population, and results were consistent after further analyses to test the strength of the findings.

"Most prescriptions written by the majority of providers are below recommended thresholds, suggesting that most US providers are careful in their prescribing," write the authors. "However, a small portion of providers account for a highly disproportionate proportion of opioids."

Rather than impose rigid thresholds on most providers, who generally prescribe opioids safely, they suggest interventions should focus on the top 1% of providers and their patients.

Interventions should also focus on improving patient care, managing patients with complex pain, and reducing comorbidities, they conclude.