With this release, the Canadian Medical Association Journal (CMAJ) teases one of its newly published studies that appears to be great news for babies and their parents: the promise of relieving pain from vaccination. Specifically, the news release promotes the idea of educational videos (i.e. for managing infant pain), giving a baby sugar water, and — most effectively, according to a study — spreading lidocaine cream on a baby’s skin before a round of injections. The release would have benefited from a clearer description of what type of lidocaine was used (over-the-counter or one only available with a prescription?) and a discussion of harms and some numbers to back up the benefit claim.
Vaccines are easily a doctor’s most powerful tool in saving lives and preventing suffering, especially in young (and more susceptible) children. But they’re no fun for parents or their infants, because intense crying and pain is inevitable, and that might help explain why as many as 1 in 4 adults fear needles and 10% avoid vaccination out of that fear. The authors of the new CMAJ study, as well as those of previous studies, argue that there would be more compliance and better vaccination rates if this pain could be safely and reliably reduced. However, while lidocaine is most often used to numb sunburn, bug bites, and other skin pain, it also receives one of the FDA’s strongest warnings against its use on kids (though for teething pain, not topical skin creams).
No dollar signs here, though an over-the-counter tube of lidocaine cream usually costs under $10. We’re not sure from the release if an OTC cream was used or one of the proprietary, prescription-only products.
There were no absolute numbers included here, and that’s a big omission. The CMAJ study notes how, per a score of 1-10 on the Modified Behavioral Pain Scale (MBPS) — with 10 being the highest level of pain — an improvement of 0.6 is generally necessary for doctors to change their practice on a procedure. Yet the study showed that the absolute effect of lidocaine cream (plus an educational video and sugar water) on vaccination pain was less, at 0.5.
There’s also this: As noted in the comments at a NEJM Journal Watch post, it can take more than an hour for lidocaine creams to make pain relief effective for tissues deeper than the skin (and vaccines are often injected into muscles). For the CMAJ study only about 20 minutes elapsed, since the cream was applied right before parents watched a 20-minute video and taken off immediately afterward.
Potential harms weren’t addressed at all. While lidocaine is most often used to numb sunburn, bug bites, and other skin pain, the Mayo Clinic describes it as a last resort for relieving topical pain in kids under the age of 3. Lidocaine can be toxic when ingested by children when used for oral pain relief during teething. The FDA has tracked some cases of seizures and even death linked to use of the drug.
The release provides a good summary of the study describing it as a randomized controlled trial of 352 healthy infants who were randomized into four groups.
Although the study did not evaluate lidocaine cream alone as one of the four experiment groups, the release does note consistently that the lidocaine was given in combination with other treatment strategies.
We didn’t see anything that would cause a reader distress or blow the problem of vaccine injection pain out of proportion.
The release does note that Pfizer funded the research, but you’ll only see that listed on a sidebar of the EurekAlert!-hosted version of the news release. The disclosure isn’t included in the release text, meaning it probably won’t be noted in subsequent reprints of the release or many articles launched by the news release.
Perhaps more importantly, the release — unlike the study itself — doesn’t disclose that the lead author received a research grant from Pfizer, which makes a lidocaine-containing line of products called Lignocaine. This is an important consideration not only in terms of sponsorship transparency; it also raises the question of whether Lignocaine results can be generalized to other lidocaine products.
The release compares a range of methods for alleviating vaccination pain in infants — training parents on how to soothe a child, giving the child sugar water, and applying lidocaine cream. We’re not told the contents of the training video but presumably it focused on holding, verbal soothing and nursing. In its practice guidelines, the CMAJ recommends breastfeeding during a vaccine injection to mitigate pain in infants.
Lidocaine creams come in many different over-the-counter products but it’s unclear whether the lidocaine formulation used in the study is the same as one might find over-the-counter, or if it’s EMLA (a cream using equal parts lidocaine and prilocaine) or another prescription product.
A randomized controlled trial comparing different methods of pain relief (placebo control, the video, sugar water, and lidocaine in combination with the sugar water and video) appears to be a novel approach to studying pain relief in infants.
The release could have done a better job explaining why researchers chose to combine some methods but not test lidocaine alone. There is other published research available on treating “procedural pain” in infants and children, but these are mostly focused on venipuncture. There are many studies on sucrose (but almost all in neonates), some on other soothing actions (presumably what was in the video), and some on topical anesthetics. However, the intramuscular aspect of immunizations may make them different. Nonetheless, many pediatricians already use a topical agent (usually EMLA) for immunizations.
Nothing over-the-top here, though we feel the news release’s headline isn’t supported by the release itself, let alone the study.