Increased Sympathetic Nerve Activity in COPD is Associated with Morbidity and Mortality

Chronic obstructive lung disease (COPD) is a major cause of comorbidity and mortality. Systemic effects, such as sympathetic activation, might contribute to progression and severity of the disease. This study investigated whether increased sympathetic activity is associated with increased long-term morbidity and mortality with COPD. Following a baseline registration of muscle sympathetic nerve activity (MSNA), 21 COPD patients and 21 matched healthy control subjects were contacted after a mean follow-up period of 7 years. Information about the number of hospitalizations during follow-up was obtained from patients who were still alive. Information about the time of death was collected from relatives of the deceased and local registration offices. The primary endpoint was the comparison of MSNA in living patients without hospitalizations versus MSNA in the patients who died or had at least one hospitalization due to exacerbation of COPD. At baseline, MSNA was significantly increased, whereas forced expiratory volume in 1 s and arterial oxygen tension (PaO2) were significantly decreased in patients compared with controls. MSNA was significantly higher in COPD patients who had reached the combined endpoint of hospitalization or death during follow-up (n = 12) compared with patients who were still alive at follow-up and had not been hospitalized (n = 8): 60.3 +/- A 15.8 (SD) bursts/min versus 40.5 +/- A 17.5 bursts/min; p = 0.022. Our data suggest that sympathetic activation is related to adverse outcome in COPD. Although this finding has to be replicated in larger studies, it implies that neurohumoral activation could be a potential therapeutic target in COPD.