Anemia versus disease activity as a cause of fatigue in rheumatoid arthritis, Escobar et al, 2010
Full Text of ArticleWhat did they study?
Approximately 50% of RA patients are anemic, which is thought to be the result of inflammatory processes associated with the disease. Microbes require iron to grow, so it may be part of the natural immune system to actively reduce the amount of iron in the blood in response to infection.
This study evaluated 130 RA patients by measuring the level of fatigue using a 40 question survey in which patients rank on a scale of 0-4 their responses to questions about their physical, social, emotional and functional status. The lower the score, the more fatigued the patient is.
Patient fatigue was compared to hemoglobin levels and DAS-28 score (using number of painful and swollen joints, erythrocyte sedimentation rate (ESR) and a patient assessment of health on a scale of 0-10).
What were the results?
Fatigue score was not associated with hemoglobin levels, but was highly correlated with increases in DAS-28 score. The researchers further analyzed the data to look at whether ESR, joint pain/swelling, or global health score were the aspect of the score that correlated with increased fatigue and found that while ESR was not related to fatigue score, increases in the number of painful and swollen joints or global health scale were associated with higher levels of fatigue.
What does this mean?
I discount the correlation of patient's reported global health score, since that will naturally be correlated with increased levels of fatigue--if the patient is fatigued they are more likely to feel depressed and thus subjectively score their disease as more severe. However, it is interesting that higher disease activity is more associated with fatigue than low blood iron levels. It indicates that while increasing iron levels is important for overall health, the key to reducing fatigue is managing inflammation. While DMARDs may have some anti-inflammatory effects, especially in the long term, it is clear that patients may need multiple therapies to maintain quality of life.
