Individualizing Pain Treatment: Start with Gender?

Individualizing Pain Treatment: Start with Gender? – ASPS 2018

When evaluating a new patient with pain, doctors may first think about the location of the pain, the potential mechanism, the severity or the age of the patient.

Inna Belfer, MD, PhD, has another idea: first, consider gender. “The approach to the patient should be individualized, first of all, based on sex, then age,” said Dr. Belfer, health scientist administrator at the National Institutes of Health (NIH) Office of the Director.

This seems so obvious to me that I’m surprised it’s worth an expert’s time to write about it.  

We should not treat men and women equally as an average patient,” she said, referring to the myriad of gender differences that need to be taken into account.

The problem with the “average patient”: Half of the population have two breasts and half have two testicles so the average patient would have one of each.

Yet, this is the mythological creature medical research is finding cures for, so it’s no wonder that experimentally successful medications are unsuccessful in real men and women.

She also discussed the new NIH initiative, Sex as a Biological Variable, the policy about taking gender into account in both research and clinical care.

How Different is Pain in Men and Women?

Very different, Dr. Belfer told the APS audience. Among the differences, she explained, are that men and women have unique experiences in:

  • responses to experimental pain
  • pain symptoms
  • attitudes, including reporting pain and symptoms
  • prevalence rates of acute and chronic pain
  • responses to analgesia
  • genetic influences on pain.

The sex prevalence of various painful disorders is well known, she stated.

For instance, female prevalence is seen in

  • migraine headache with aura,
  • Tic douloureux,
  • carpal tunnel syndrome,
  • Raynaud’s disease, and
  • esophagitis, to name a few.

Male prevalence is found in

  • pancreatic diseases,
  • duodenal ulcer,
  • abdominal migraine, and
  • ankylosing spondylitis, among others.

The Problem of Understudied Women

Until the past decade or so, most scientific research—not just for pain research, but all areas of research—included mainly middle-aged white males.

Studying sex differences is crucial not only to fight stereotypical views, such as the pain is all in your head, but also to understand brain-related disorders with sex differences in their incidence or nature, and to explain contradictory findings, she said.

Considering Known Differences in Practice

While research on sex differences in pain and pain treatment is not yet common, researchers have looked at some differences that may be helpful in assessing patients.

For instance, these differences have been noted in opioid analgesia, according to Dr. Belfer:

  • In a meta-analysis of 25 studies, researchers found greater opioid consumption in men than in women.
  • Morphine had a slower onset of action in women but was more potent.
  • K-opioids (pentazocine) may provide more pain relief in women.
  • Women carrying the HPS haplotype may be the most sensitive to capsaicin-induced pain.

SABV Policy May Help

Pain research studies, as well as research in other areas, will have increased focus on gender differences, due to the NIH ruling about Sex as a Biological Variable, which took effect in January 2016.

Under this grant program, the NIH expects that ‘‘sex as a biological variable will be factored into research designs, analyses, and reporting invertebrate animal and human studies.”


In terms of pain sensitivity, ‘‘sex differences reveal themselves early in life,” said Rollin Gallagher, MD, MPH

“Epidemiological studies show great differences in several [pain] conditions indicating that gender may be responsible for vulnerabilities to pain conditions and require different approaches.”

Original article: Individualizing Pain Treatment: Start with Gender? 

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