LBP and chronic obstructive pulmonary disease: Univariately, COPD was associated with sputum neutrophilia (OR 1.09 [1.04–1.15]), elevated IL-8 (OR 1.4 [1.1–1.7]), sTNF-R55 (OR 1.005 [1.0–1.01]) and sTNF-R75 (OR 1.005 [1.0–1.01]) in sputum, and raised levels of IL-8 (OR 2.5 [1.01–6.0]), sTNF-R55 (OR 7.6 [1.6–35.1]), sTNF-R75 (OR 10.2 [2.2–47.8]) and LBP (OR 1.1 [1.04–1.25]) in plasma,.