Nine-Year Follow-Up of Interleukin 6 in Chronic Obstructive Pulmonary Disease - Complementary Results from Previous Studies.

Abstract

BackgroundSystemic manifestations of chronic obstructive pulmonary disease (COPD) are related to increased systemic inflammatory process; however, it is not entirely clear how much they are related and how the systemic inflammation, in particular interleukin-6 (IL-6), is associated with exacerbation and mortality risk.ObjectiveTo evaluate the role of IL-6 in COPD patients over nine years.Study Design and MethodsA total of 133 COPD patients were assessed at baseline between 2004 and 2006 and reassessed after three and nine years through clinical evaluation, comorbidities, hematological blood count and IL-6 analysis.ResultsAfter nine years, 19 patients lost the follow-up and were not possible to identify the date of death of four patients; 12 refused to participate and 1 could not be involved due to recurrent exacerbations. Therefore, 33 patients were included in the reassessment after nine years of follow-up and 92 patients were included in the Cox mortality analysis with IL-6 as a time-dependent covariate. Regarding the inflammatory profile, in patients who survived after nine years, there was a significant increase in IL-6 [0.4 (0.2–0.8) vs 5.7 (3.4–11) pg/mL; p < 0.001] and reduction in lymphocyte count [2.1 (1.6–2.4) vs 1.4 (1.2–2.1)10^9/L; p < 0.01] with an increase in the neutrophil/lymphocyte ratio (2.0 ± 0.7 vs 2.7 ± 1.2; p = 0.003). The Cox mortality model did not show a statistical significance influence of IL-6 assessed during the follow-up.ConclusionThere was a progressive increase in IL-6 during the follow-up, however, without influence on mortality.