There were 40 million children under the age of 5 and more than 340 million individuals between the ages of 5 and 19 whose BMI put them in the categories of overweight/obesity in 2018, according to the World Health Organization. Despite the increasing proportion of pediatric patients with obesity, there is little data about pain sensitivity and analgesic requirements in this population.
“Studies in adults indicate that patients with obesity may have different opioid requirements following surgery to achieve optimum recovery,” states Alparslan Turan, MD, Vice Chairman of Outcomes Research and Staff at Cleveland Clinic’s Anesthesiology Institute. “The research suggests physiological and pharmacogenetic differences that might explain the altered pain perception and analgesic requirements in postoperative adults with obesity; however, we had no idea how this might apply to children and adolescents.”
To address this gap in the literature, together with collaborators, Dr. Turan conducted a retrospective analysis of more than 800 opioid-naïve patients between the ages of 8 and 18 who had elective, noncardiac surgery with an inpatient stay of at least 48 hours at Cleveland Clinic between 2010 and 2015.
The relationship between BMI and pain varied across procedures. For general/urologic procedures, mean pain score was 2.3 ± 1.8 (based on a numerical response scale ranging from 1 to 10), with no association between BMI and pain reports. Similarly, there was no association between BMI and pain reports for orthopaedic procedures (mean pain score was 3.2 ± 1.6) or neurospinal procedures (mean pain score was 3.5 ± 1.7). The only category in which BMI appeared to impact pain reports was in neurocranial procedures. Mean pain score following neurocranial procedures was 3.5 ± 1.7. In this cohort, the pain score increased 0.7 per 5 percentile point increase in BMI.
“Adult patients with obesity do seem to feel pain more than patients without obesity, and the evidence suggests that these patients may have increased opioid requirements. In our study of pediatric patient, however, we found no clinically significant association between increased BMI and higher pain scores across most noncardiac procedures,” Dr. Turan states.
In terms of opioid requirements, as BMI percentile increased, mean estimated post-operative opioid use actually decreased. “We were surprised to see that patients with obesity consumed 30% less opioids than patients without obesity,” Dr. Turan notes.
“We expected to see that pediatric patients with obesity were more like adult patients with obesity – that they needed more opioids. However, the opioids seem to work differently in the pediatric population. Whether or not analgesic needs change with weight loss – say if a child with obesity loses a significant amount of weight in adolescence or adulthood – remains unclear. It should be noted that unlike in adults, pediatric patients are usually dosed by weight, and this approach was considered in the current study. So the correct interpretation is that pediatric patients with obesity require similar doses of analgesic medications per kilogram, as children without obesity.”
“Clinicians should note that, in our study, there was no clinically important association between BMI and pain sensitivity or opioid requirements. It seems physicians can follow a similar approach when dosing analgesics in the perioperative period for pediatric patients with and without obesity,” Dr. Turan says.
“People often think of children as ‘small adults,’ and it’s important for clinicians to understand that’s not the case. This study helps to clarify that opioid dosing should be based on actual body weight and will, hopefully, lead to a more standardized approach to dosing in obese patients,” says Jason Roberston, MD, a surgeon with Cleveland Clinic Children’s. “In recent years, there has been a push on a national level to reduce opioid use and be more thoughtful about our prescribing practices. In conjunction with the pain service, my partners and I have adapted multi-modal strategies of postoperative pain control that rely heavily on non-opioid analgesics. In fact, we control postoperative pain in many patients without any opioids at all.”