Cachexia not linked to increased systemic inflammation in COPD
MedWire News: Results from a Norwegian study counter the theory that cachexia in patients with chronic obstructive pulmonary disease (COPD) is mediated through an increase in systemic inflammation.
Writing in the European Respiratory Journal, Tomas Eagan (Haukeland University Hospital, Bergen) and team explain: "Previous studies suggest a relationship between systemic inflammation and body composition in COPD."
However, they add: "Although an increase in systemic inflammation is arguably the prevailing theory for loss of lean body mass in some COPD patients, this theory remains unproven."
To investigate further, the team studied 409 stable COPD patients (249 men), aged 40-75 years, with Global Initiative for Obstructive Chronic Lung Disease (GOLD) stage II-IV disease.
Each participants' fat free mass index (FFMI) and fat mass index (FMI) were calculated, and their plasma levels of C-reactive protein (CRP), soluble tumor necrosis factor receptor 1 (sTNF-R1) and osteoprotegerin (OPG) were measured.
The mean FFMI and FMI in men and women were 18.4 and 14.8 kg/m2, and 7.3 and 10.1 kg/m2, respectively. Mean plasma levels of CRP, sTNF-R1, and OPG were 7.7 and 8.9 µg/ml, 758 and 699 pg/ml, and 5.7 and 6.0 ng/ml, respectively.
Analysis revealed that, in both genders, CRP and sTNF-R1 increased significantly with increasing FFMI and FMI. In contrast, OPG levels decreased with higher FMI, but there was no significant association between FFMI and OPG.
The findings remained true after accounting for age, smoking, FEV1, Charlson Comorbidity Index, hypoxemia, and use of inhaled steroids, the researchers note.
Eagan and team conclude: "The current study does not support the theory that cachexia in COPD patients is mediated through an increase in TNF-α related systemic inflammation. Rather, the study results allow the hypothesis that high fat mass may also be a predictor of high plasma levels of CRP and sTNF-R1 in COPD patients."
They add: "The relationship between FMI and OPG in COPD patients is novel, and could be an indication that fat metabolism is a factor in the development of osteoporosis in COPD patients. However, these findings need to be confirmed in longitudinal studies."
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By Mark Cowen