Fibromyalgia Pain, Fatigue Greatly Affect Perceptions of Physical Ability, Study Finds

Fibromyalgia Pain, Fatigue Greatly Affect Perceptions of Physical Ability, Study Finds

Fibromyalgia-related pain and fatigue can explain much of the variance found in patients’ perceptions of their physical performance and abilities, according to a study, “Perceived function and physical performance are associated with pain and fatigue in women with fibromyalgia,” published in the journal Arthritis Research & Therapy.

Fibromyalgia, a condition characterized by chronic and widespread muscle pain, affects between 4 percent and 10 percent of the U.S. population, mostly women. While pain is the defining characteristic for diagnosing fibromyalgia, fatigue is also a common complaint in this patient population.

To determine the degree to which pain and fatigue are associated with perceived function (daily tasks like pouring coffee or getting dressed) and physical performance, researchers at the University of Iowa recruited 94 women with fibromyalgia, ages 18 to 17. Participants had a diagnosis of fibromyalgia confirmed using ACR 1990 criteria with 11 of 18 tender points (TeP), subjective pain greater than or equal to 4 on a scale of 10, a history of cervical or lumbar pain, and a current stable treatment regimen for four weeks prior to study enrollment and a projected two-month stable regimen. Patients underwent treatment using transcutaneous electrical nerve stimulation.

The researchers assessed pain and fatigue using the Numeric Rating Scale (NRS) for resting, movement and combined measured; assessed perceived function using the Fibromyalgia Impact Questionnaire Revised-Function Subscale (FIQR-Function), the Multidimensional Assessment of Fatigue-Activities of Daily Living (MAF-ADL), and SF-36 Physical Function Subscale (SF-36-PF); and assessed physical performance using the six-minute walk test (6MWT) and the Five Time Sit To Stand (5TSTS) test. Other assessments included the Pain Catastrophizing Scale, and the Tampa Scale of Kinesiophobia to measure fear of movement.

Results revealed no correlation between age and weight with any control variables, but psychological traits were significantly associated with each other, including anxiety, catastrophizing pain, and depression. There was a moderate correlation between pain and fear of movement, and a weak correlation between depression and anxiety.

Pain and fatigue were found to be significantly and independently associated with and predictive of perceived function and physical performance. “In our models, pain and fatigue, along with demographic and psychological variables, explain up to 43 % of the variance observed in perceived function and up to 41 % of the variance observed in physical performance,” the authors reported in the study.

Age, weight, and psychological factors also accounted for 11 percent to 22 percent of variance found in perceived function, they reported.

“Overall, self-reported movement pain and fatigue intensities explained a higher proportion of the variance observed in all three perceived function assessments [than] self-reported resting pain and fatigue intensities. This was most notable for the resting pain scores as resting fatigue typically explained a greater proportion of perceived function than resting pain. However, movement pain intensity was often superior to movement fatigue intensity when they were considered in isolation,” the researchers wrote, according to a news release.