March 2, 2020

Experts Identify Knowledge Gaps in Chronic Osteoarthritis Pain in Women

By Emily Ortman, SWHR Communications Director

Chronic pain disproportionately affects women, and substantial research demonstrates that differences exist between women and men in experience, management, and treatment for pain conditions such as osteoarthritis (OA).

Joint disease and joint pain are the No. 1 reason for doctor visits, and musculoskeletal pain overall is the No. 1 cause of years lived with disability. Osteoarthritis is a huge contributor to this, affecting half a billion people worldwide. For hand, hip, and knee OA, incidence in women outweighs that in men. “No matter what region of the world and what age group, women have a higher prevalence of clinical OA than men,” said Tuhina Neogi, MD, PhD, chief of rheumatology and professor of medicine and epidemiology at Boston University School of Medicine.

To delve deeper into OA and its impact on women, SWHR brought together a diverse group of researchers and clinicians for a closed-door roundtable meeting to identify unmet needs and knowledge gaps in understanding the relationship between pain and function in women with OA.

Roundtable participants discussed the current state of the science on chronic OA, including research about the effects of this condition on women’s functioning and quality of life. The group recommended future directions for research, policy, and education to ultimately improve care for women with OA.


Needs in OA Research and Treatment

1. Better understanding of normal joint aging and OA disease progression

No study has been conducted to provide a baseline for normal joint aging, Neogi said, making it difficult to understand how OA progression compares with changes occurring as part of normal aging. Further, it is not well understood how changes in joint structure over time coincide with changes in pain and function. “There is a structure‑symptom discordance in osteoarthritis where people can have terrible looking X-rays, but they don’t have much knee pain, or their X-rays look fine, but they have a lot of knee pain,” Neogi said.

A better understanding of the disease trajectory over time and how it may differ for women and men could help lead to sex-specific interventions for OA, said Roger B. Fillingim, PhD, professor and director of the University of Florida Pain Research & Intervention Center of Excellence.


2. Inclusion of female animals and disease models in basic research

Advancing OA research will require better animal models of disease and improving consideration of sex as a biological variable, said Anne-Marie Malfait, MD, PhD, professor of medicine and director of the Laboratory for Translational OA Research at Rush University. Most OA research is conducted in male rodents, she said, in part because female animals do not reliably develop OA in the most commonly used surgical disease model. There is a clear need for disease-specific models for OA pain. In fact, Malfait pointed out that the OA pain literature in rodent models is very limited overall. “People say, well, there’s not much on females,” she said. “I would add there’s actually not much at all in comparison with research into joint damage.”


3. Improved methods for measuring pain and function

The experts agreed on the need for more accurately assessing OA pain and function by employing and creating better measurement tools. People usually seek medical care because of pain, yet pain assessment tools often only ask about pain severity, which may not be sufficient to capture the full impact and experience of pain.

“Function is actually more important to measure and to track over time,” said Daniel Clauw, MD, director of the Chronic Pain and Fatigue Research Center and professor of anesthesiology, medicine, and psychiatry at the University of Michigan. He suggested technology like wearables could be used to better track function over time. In addition, Fillingim said that pain during function is not systematically assessed in the clinic or research studies, and that implementing methods that measure movement-evoked pain would provide important insights.


4. Therapies tailored to the patient’s pain mechanism

Clauw outlined three different pain mechanisms: nociceptive (inflammation or damage), neuropathic (nerve damage or entrapment) and centralized/nociplastic (a disturbance in central nervous system pain and sensory processing). OA pain is complex, the experts noted, with peripherally-driven nociceptive pain potentially coexisting with centralized pain.

Centralized pain appears to be more prevalent in women, Clauw said, adding that many therapies used in clinical practice don’t typically work for this type of pain. He pointed to research showing that patients who appeared to suffer from centralized pain had a greater likelihood of failing to respond to knee or hip surgery. Better tools are needed to identify which mechanisms are contributing to an individual’s pain experience in OA, and then treatments should be tailored to those specific pain mechanisms, Clauw said.


5. Support for multimodal and nonpharmacological treatment approaches

People with OA often have multiple comorbidities and require a multimodal approach to managing their symptoms. First-line therapies for OA includes weight loss, physical activity, and physical therapy. Fillingim advocated for better educating and equipping patients with self-management skills so they spend less time having to go to doctor. Daniel L. Riddle, PT, PhD, a professor of physical therapy, orthopaedic surgery, and rheumatology at Virginia Commonwealth University, added that healthy lifestyle interventions to address modifiable risk factors can positively influence not only life expectancy but quality of life.

OA patients may also benefit from approaches used more broadly for chronic pain management, such as cognitive behavioral therapy (CBT), the experts said, but they noted that health insurance coverage for this type of chronic pain care model is generally insufficient. Those with OA who also have centralized pain would especially benefit from a holistic approach, as opposed to being shuttled from specialist to specialist for their various pain complaints.


6. Addressing medical provider biases

Throughout the health care system, implicit biases against women create barriers to care, and chronic pain conditions like OA are no exception. Women’s complaints are often taken less seriously than men’s and they live longer with the burden of OA, Neogi said. Although more women get joint surgery than men, they are still under-represented given the much higher prevalence of OA in women. Of the people who would potentially benefit from surgery but haven’t gotten it, those people are mainly women, Riddle said. Women tend to have somewhat more pain and functional loss prior to surgery, he added.

There’s also evidence that pain coping differs across sex, Fillingim said, noting that while research shows women are more pain sensitive, anecdotally he’s heard clinicians say women are more pain capable and tolerant. The experts suggested the need for research into potential gender bias in the treatment of OA, such as in recommendations by doctors and surgeons on which patients should undergo surgery.