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Duration of treatment rather than dose more strongly associated with opioid misuse after surgery

Findings may prompt change in opioid prescribing patterns after surgery

BMJ

Prescribing higher opioid doses for shorter durations may be a more effective way to treat pain after surgery, while minimising the risk of longer term misuse and addiction, suggest US researchers in The BMJ today.

Opioids are often given to patients to relieve pain after surgery. Guidelines recommend taking only low doses for a short time, as opioids can cause problems when taken for long periods of time.

Yet opioid misuse is increasing globally. Overprescribing is thought to be a contributor, but it is unknown how opioid prescribing habits by doctors are related to rates of misuse.

So a team of US researchers, led by Gabriel Brat at Harvard Medical School in Boston, set out to examine the association between opioid prescription refills (repeat prescriptions) after surgery and misuse.

They identified just over one million commercially insured US patients - none of whom had a history of misuse or ongoing opioid use - who underwent routine surgery between 2008 and 2016.

The team used administrative data to track prescription refills for oral opioids after discharge and diagnostic coding data to identify opioid dependence, abuse or overdose.

A total of 568,612 (56%) patients received prescriptions for postoperative opioids, 90% of which were filled within three days of hospital discharge. In the subsequent follow-up period spanning an average of around two and a half years, misuse was identified in 5,906 patients (0.6% or 183 per 100,000 person years).

Analysis of the data showed that overall rates of misuse were low, but seemed to increase with each opioid prescription refill.

For example, after taking account of other potentially influential factors, each opioid prescription refill was associated with a 44% increase in misuse and each additional week of opioid use was associated with a 20% increase in opioid misuse among these patients.

The data also suggest that duration of the prescription rather than dose is more strongly associated with ultimate misuse in the early postsurgical period, with even high doses associated with only mild increases in risk of misuse when duration was short.

These results remained largely unchanged after further sensitivity analyses, prompting the researchers to suggest that giving moderate to higher opioid doses for shorter durations may be a more effective way to manage pain after surgery, while minimising the risk of misuse and addiction.

This is an observational study, so no firm conclusions can be drawn about cause and effect, added to which the information on misuse is drawn from administrative data and the findings were limited to insured adults in the US.

Nevertheless, the study was large, and the researchers were able to account for a range of potentially influential factors. As such, they say their analysis "provides a broad evidentiary framework to inform clinician behavior and promote protocol development."

And they suggest that "further research of this relation is needed to determine how initial treatment regimens can minimize misuse and addiction."

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