Women and men experience and express pain differently, and this can create challenges to treating women's pain effectively.
Increased awareness about sex differences in pain has helped, but many women still face barriers to getting proper pain treatment, said Padma Gulur, MD, professor of anesthesiology at Duke University School of Medicine in Durham, North Carolina.
"Women often find themselves being labeled as very emotional when they express their concerns," Gulur explained. "This tends to take away from their ability to develop therapeutic relationships with their providers and impacts their self-advocacy."
A 2015 American Society of Anesthesiologists literature review found that despite a wide range of effective treatments, women often suffer needlessly from pain and tend to treat it with medications that may be ineffective and possibly harmful. And in the 2019 HealthyWomen chronic pain survey, 38% of women who experienced pain for more than 3 months did not think their healthcare provider took their pain seriously. About 45% of women said their provider somewhat understood their chronic pain, and 17% said their provider did not understand their pain at all.
Sex and Gender Differences
Both sex (biology) and gender (psychosocial construct) can impact the perception and expression of pain, noted Kim Templeton, MD, professor of orthopedic surgery at the University of Kansas Medical Center in Kansas City.
"Sex can impact the prevalence of conditions that result in painful stimuli," she said. "Women are more likely than men to develop many of the conditions that can lead to chronic painful stimuli like osteoarthritis and rheumatoid arthritis."
"Sex also impacts how the spinal cord and brain interpret these painful stimuli, which has been noted on functional brain imaging," Templeton added. "Sex-based differences have also been identified among neonates subjected to necessary painful procedures, so this seems to be something hardwired into the brain."
Moreover, spinal cord and brain processing of pain signals can change over time, and can be affected by factors like age, additional painful experiences, estrogen and other hormones, or other comorbidities like depression, anxiety, or post-traumatic stress disorder (PTSD), she noted.
This is especially important for women, who "are more likely to experience these co-morbidities, as well as be victims of interpersonal violence or other forms of violence that can lead to painful injuries or depression, anxiety, or PTSD," Templeton said. A study presented at the 2019 American Pain Society scientific meeting, for example, found that nearly three of four women who experienced sexual assault had new or worse pain a week later, and in most cases, that pain persisted for weeks.
Gender, on the other hand, may affect how a person describes or expresses pain, Templeton noted. In some cultures, it may be more socially acceptable for women to complain about pain. "Perhaps higher prevalence of chronic pain in women compared to men reflects how they are expressing what they are going through," she said. "At a subconscious level, women also may be attempting to self-medicate their depression, anxiety, or PTSD with opioids."
"There is also emerging research that women and men respond to opioids differently because of differences in the mu-opioid receptor; in laboratory animals, males may have more rapid onset and longer pain relief than do women," she said. "All of this makes treatment of chronic pain challenging, because of the number of factors that influence pain perception and expression and response to treatment."
Many studies of sex-based differences in pain have used healthy volunteers who were subjected to acute painful stimuli, and while it's hard to determine how this translates into experiences of women with chronic pain, their results are telling. For years, researchers led by Roger Fillingim, PhD, of the University of Florida in Gainesville, have studied pain differences between men and women, recruiting healthy people to take part in experimental pain sessions. Consistently, they have found that women report the same stimuli to be more painful than men.
A Treatment Gap?
Is there a gap in pain treatment between women and men? "Maybe, but it isn't for lack of attempting to control women's pain," Templeton observed.
"Given how complex the issue is, standard approaches to treating acute pain after an injury likely do not translate into how to treat women with other health conditions who have chronic pain," she said. "This requires a multi-disciplinary and usually trauma-informed approach."
The field needs additional research to understand how sex and gender affect pain, "to better understand how depression, anxiety, and PTSD influence the experience of pain from a sex- and gender-based perspective, and to better understand differences between men and women in response to opioids and other medications and modalities," Templeton said.
There also needs to be more healthcare professional education in sex- and gender-based differences in pain, she added.
Recognizing and supporting sex differences is an important part of effective pain management, Gulur noted. "The pain experience is unique to each individual," she said. "Recognizing the biopsychosocial interplay is critical for providers managing this condition."