TNF and chronic obstructive pulmonary disease: When all aforementioned parameters were combined with IL-1β, IL-6 and TNFα in network analysis, it was shown that not all patients with stable COPD have increased systemic inflammatory parameters, and even already well-known inflammatory parameters like CRP and Fbg were increased in only 21% and 34% of COPD patients, respectively, in comparison to the 95th percentile of healthy non-smokers.