Among individuals with the degenerative arthritis commonly referred to as osteoarthritis (OA), pain is what patients describe as having the largest impact on the performing of daily activities---and the main cause of visits to the doctor. While it is therefore not surprising that the main focus of treatment would obviously be on the relief of that pain, such an approach may be too narrow for the optimal management of OA—or any other disease for that matter. It seems both patient and physician are neglecting the negative role fatigue plays in the daily lives of the lives of patients suffering from OA. Fatigue can be a predictor of bad things to come, particularly in an older population, as it is one of the five clinical indicators in most models of frailty, the others being:
• Impaired strength
• Impaired endurance
• Impaired balance
• Increased vulnerability to trauma or other stressors.
Relevant to OA, when fatigue in older adults has been measured as tiredness in the performance of daily activities, it predicted the development of mobility problems, dependence in the performance of daily activities, and the risk of an (early) death.
Health care providers—and perhaps patients themselves—buy into the assumption that pain causes fatigue, and therefore the relief of that pain will result in a corresponding reduction in fatigue. However, it may be that this assumption is flawed, because pain and fatigue may have different etiologies and a complex interplay. Interestingly, fatigue has been cited as the primary reason that an older adult might limit his or her activity, and thus the relationship between fatigue and activity must be better characterized. In fact, previous studies have found that when assessing symptoms within and across days (“momentary fatigue” and pain) and related physical activity, it was found that fatigue was more related to reduced physical activity than pain in women afflicted with OA. In addition, researchers found that women with OA were 4 times more likely to experience an increased level of fatigue after an intense session of physical activity compared with matched healthy patients.
It is crucial that those who provide medical care to patients be educated as to the manner in which fatigue is associated with subsequent levels of day-to-day activity. If medical and mental health professionals can better understand the mechanisms of behavior adjustment and activity levels in the face of fatigue, then perhaps patients can be offered more targeted and efficient behavioral interventions.
A study described a few weeks ago in “Arthritis Care & Research” examined the impact of fatigue on subsequent physical activity in subjects with OA. Increased momentary fatigue was associated with reduced subsequent activity, and in fact was more robustly associated with activity when compared with pain. Interestingly, pain showed no association with activity. The authors of this article stress that they recruited individuals with clinically significant baseline fatigue levels; and it was the daily experience of fatigue that was overwhelmingly associated with physical activity levels, reinforcing the assumptions that it is an important treatment target when dealing with patients with symptomatic OA.
For example, as subjects with the highest functional mobility levels experienced the strongest effects of fatigue on subsequent activity, perhaps the best treatment for similar patients would be, for example, activity pacing. Such pacing may lead to increased activity levels—and has in fact been shown to ease fatigue. In contrast, patients with lower functional mobility may be best served by having the focus of therapy turned toward the goal of improving physical function in order to decrease fatigue.
Not all patients with OA are alike. It is not just pain, but fatigue, that slows down many. Once we internalize this, we can serve our patients more efficiently, and completely.