Severity of chronic obstructive pulmonary disease and presenting rhythm in patients with out-of-hospital cardiac arrest.

<bold>Introduction: </bold>Chronic obstructive pulmonary disease (COPD) is associated with a non-shockable rhythm as presenting rhythm in out-of-hospital cardiac arrest (OHCA). Whether the severity of the underlying disease is related to presenting rhythm is unknown. We hypothesized that increased severity of COPD in OHCA patients is associated with an increased prevalence of non-shockable rhythm.<bold>Methods: </bold>This study included OHCA patients ≥40 years from the Danish Cardiac Arrest Registry (2001-2014). Population-based registries were used to identify chronic diseases and drug prescriptions. COPD was defined as a COPD diagnosis or pharmacological therapy for COPD. The severity of COPD was based on either 1) pharmacological therapy (mild/moderate/severe), 2) admission for exacerbation, 3) prescription for corticosteroids, or 4) forced expiratory volume in 1 s (FEV1). For each of these, a multivariable logistic regression model was used to estimate odds ratios (ORs) for a non-shockable rhythm.<bold>Results: </bold>Of 33,228 patients with OHCA 7789 (23.4%) had COPD. Of these 6702 (86.0%) had a non-shockable rhythm. Compared to patients without COPD, mild COPD was associated with a non-shockable rhythm (OR = 1.46, 95%CI 1.29-1.65). This association was more pronounced for moderate (OR = 1.78, 95%CI 1.45-2.19) and severe COPD (OR = 2.01 95%CI 1.82-2.20). Recent admission for exacerbation (OR = 2.12, OR 95%CI 1.81-2.49) or prescription for corticosteroids (OR = 1.82, 95%CI 1.55-2.14) was also associated with a non-shockable rhythm. FEV1 ≤ 50% was associated with a non-shockable rhythm compared to FEV1 > 50% (OR = 1.74, 95%CI 1.07-2.82, n = 1122).<bold>Conclusion: </bold>Incremental severity of COPD is associated with increasing prevalence of a non-shockable rhythm as presenting rhythm in OHCA patients. [ABSTRACT FROM AUTHOR]