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Whats New in the
Patient Safety World
December 2023
Postop Gabapentin
No Better Than Placebo
Over the past couple
decades, gabapentin and gabapentinoids have been
widely used in management of pain. At the beginning, they were used primarily
for neuropathic pain. But now theyve been used for almost any sort of pain.
Recently, there has been a trend toward using gabapentinoids
postoperatively in hopes that use of opioids might be reduced. Because of this,
a randomized controlled clinical trial was designed to address this question.
The GAP trial randomly allocated patients undergoing cardiac, other thoracic, and
abdominal surgery into one of two groups. Those in the first group were treated
with gabapentin one hour before surgery and for two days after surgery. Those
in the second group were treated with an identical looking dummy pill (placebo)
at the same timepoints. Pain levels were assessed by asking patients one, four
and 12 hours after surgery and then twice a day until they were discharged from
hospital. Patients were also followed up until discharge to find out if they
have taken opioid pain killers, as well as to assess their quality of life
after four weeks and four months.
Results of the GAP trial were recently presented at an abstract session at the American Society of Anesthesiologists annual meeting (Gever 2023). No clinically significant benefit was seen for the active drug in terms of length of hospital stay, opioid use, patient-reported acute pain, or quality of life. Trends toward less severe pain, when assessed 4 months after surgery, and better quality of life were seen in the placebo group.
GAP randomized 1,196
patients 1:1 to receive gabapentin or placebo for 3 days, starting immediately
before surgery. The first gabapentin dose was 600 mg, then it was given at 300
mg twice daily on days 1 and 2 after surgery. Median patient age was about
68, and roughly two-thirds were men. Median length of stay, the primary
outcome, was 5.94 days in the gabapentin group versus 6.15 days in the placebo
group (p=0.26). That minor difference was the same with all three surgery
types.
Opioid use did favor
gabapentin for non-cardiac thoracic and abdominal procedures over the first few
post-operative days, being roughly 30% lower at several time points. But it was
felt that this was statistically significant but not clinically significant.
Similar differences were seen with patient-reported acute pain, but these were
not felt to be clinically important, representing less than one point on the
standard 10-point scale.
Longer-term
evaluations of chronic pain and quality of life, which trended against
gabapentin, also indicated that the differences were relatively small in
clinical terms.
Adverse event rates
did not differ at all, recorded for about one-third of patients in both
treatment groups. That is somewhat surprising. Over the past 5 years, weve
seen more and more examples of the downside of gabapentinoids
(see our prior columns listed below). There were several reports of increased
risk of respiratory depression when gabapentinoids
were used in conjunction with opioids.
Researchers
acknowledged study limitations such as restriction to major body-cavity
surgeries, meaning that the study is not relevant to joint replacements (when
painkillers are often required for much longer than 2 days) or any kind of
ambulatory procedure, and the inflexible dosing protocol.
Some of our prior columns on safety issues with gabapentinoids:
·
November
2017 Bad Combination: Gabapentin
and Opioids
·
March
2019 Gabapentin and Pregabalin on
the Radar Screen
·
January
2020 FDA Warning on Gabapentinoids
·
February
25, 2020 More on Perioperative Gabapentinoids
·
January
2021 Gabapentinoids Again
·
June
2022 Gabapentin and Overdoses
·
September
27, 2022 More Bad News for Gabapentin
References:
Gever J. Gabapentin as Post-Op Painkiller Gets a Cold Shower Placebo-controlled trial offers no justification for widespread use. MedPage Today 2023; October 15, 2023
https://www.medpagetoday.com/meetingcoverage/asa/106814
Gabapentin in post-surgery pain
https://www.isrctn.com/ISRCTN63614165
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