Woolie
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Association of C-reactive protein and interleukin-6 with new-onset fatigue in the Whitehall II prospective cohort study
Cho, H. J., Kivimäki, M., Bower, J. E., & Irwin, M. R. (2013).
Psychological medicine, 43(08), 1773-1783.
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This is potentially important work. The absence of biomarkers associated with fatigue severity has been used to argue that it is a largely due to psychological factors. This is true in CFS, and also in other diseases that feature fatigue as a prominent symptom (e.g., MS, lupus). If we can find a biomarker that predicts fatigue at the group level - even if it can't fully predict how much fatigue any particular individual will experience - then that's a huge step forward.
Cho, H. J., Kivimäki, M., Bower, J. E., & Irwin, M. R. (2013).
Psychological medicine, 43(08), 1773-1783.
(Click on title for full text link)
Abstract said:Background
Although basic research on neuroimmune interactions suggests that inflammatory processes may play a role in the development of fatigue, population-based evidence on this association is limited. This study examined whether plasma C-reactive protein (CRP) and interleukin-6 (IL-6), biomarkers of systemic inflammation, predict fatigue onset.
Methods
The Whitehall II study is a large-scale cohort study conducted in 20 civil service departments in London. Plasma CRP and IL-6 were measured in 4847 non-fatigued participants at Phase 3 (1991-1993, ages 39-63 years). Fatigue was assessed using the Vitality Subscale of the 36-item Short Form Health Survey (SF-36) at Phase 3 and Phase 4 (1995-1996).
Results
During a mean follow-up of 3.1 years, 957 new fatigue cases (19.7%) were identified using the pre-established cutoff score 50 or less on the Vitality Subscale. CRP values were dichotomized as low (<1.0 mg/L) or high (≥1.0 mg/L) using the Centers for Disease Control/American Heart Association recommendations. Similarly, IL-6 values were also dichotomized as low (<1.5 pg/mL) or high (≥1.5 pg/mL). After full adjustment for sociodemographic and biobehavioral covariates, the odds ratios for new-onset fatigue were 1.28 (95% confidence interval 1.09-1.49, P=0.003) for high CRP and 1.24 (1.06-1.45, P=0.008) for high IL-6. Similar results were found when CRP and IL-6 were treated as continuous variables.
Conclusions
Plasma CRP and IL-6 were prospectively associated with new-onset fatigue, supporting the hypothesis that low-grade inflammation has a role in the development of fatigue.
This is potentially important work. The absence of biomarkers associated with fatigue severity has been used to argue that it is a largely due to psychological factors. This is true in CFS, and also in other diseases that feature fatigue as a prominent symptom (e.g., MS, lupus). If we can find a biomarker that predicts fatigue at the group level - even if it can't fully predict how much fatigue any particular individual will experience - then that's a huge step forward.