Antioxidant supplementation and atrial arrhythmias in critically ill trauma patients

Abstract

Background: The purpose of this study is to determine if antioxidant supplementation influences the incidence of atrial arrhythmias in trauma intensive care unit (ICU) patients.

Materials and methods: In this retrospective pre-post study, critically ill injured patients aged ≥18 years, admitted to a single-center trauma ICU for ≥48 hours were eligible for inclusion. The control group consists of patients admitted from January 2000 to September 2005, before routine antioxidant supplementation in our ICU. The antioxidant group consists of patients admitted from October 2005 to June 2011 who received an antioxidant protocol for ≥48 hours. The primary outcome is the incidence of atrial arrhythmias in the first 2 weeks of hospitalization or before discharge.

Results: Of the 4699 patients, 1622 patients were in the antioxidant group and 2414 patients were in the control group. Adjusted for age, sex, year, injury severity, past medical history, and medication administration, the unadjusted incidence of atrial arrhythmias was 3.02% in the antioxidant group versus 3.31% in the control group, with no adjusted difference in atrial arrhythmias among those exposed to antioxidants (odds ratio: 1.31 [95% confidence interval: 0.46, 3.75], P = 0.62). Although there was no change in overall mortality, the expected adjusted survival of patients in those without antioxidant therapy was lower (odds ratio: 0.65 [95% confidence interval: 0.43, 0.97], P = 0.04).

Conclusions: ICU antioxidant supplementation did not decrease the incidence of atrial arrhythmias, nor alter the time from admission to development of arrhythmia. A longer expected survival time was observed in the antioxidant group compared with the control group but without a change in overall mortality between groups.

Keywords: Antioxidants; Atrial arrhythmia; Critical care; ICU; Trauma.

Fig. 1

Study eligibility. There were 5679 patients were initially evaluated for eligibility. Of which 1643 patients were excluded: 663 patients had unclear exposure to the antioxidant protocol, 539 had lack of registry data, 282 had an ICU stay less than 48 hours, 109 had a past history of chronic atrial arrhythmias, and 50 had serum creatinine >2.5 mg/dL. Of the initial 5679 patients, 2414 patients were included in the control group, and 1622 patients were included in the antioxidant group.

Fig. 2

The unadjusted incidence rate of atrial arrhythmias per 100,000 patients between the control group and the antioxidant group over 11 years (2000–2011). The control group is depicted with (black squares) and the antioxidant group with open triangles. Note, in multivariable analysis (see manuscript text), we found no significant difference in the unadjusted or adjusted incidence of atrial arrhythmias in the first 2 weeks of hospitalization (or before discharge) between the antioxidant and control groups.

Fig. 3

Forest plot for adjusted time ratio of hospital mortality. This figure shows an adjusted time ratio for the control group of 0.65 (95% CI: 0.43–0.97, P = 0.04). This indicates a 35% decrease in the expected survival time in the control group compared with the antioxidant group, controlling for other factors in the model. This statistically significant difference suggests an increased survival time in patients with antioxidant supplementation compared with the control group. Also, patients with congestive heart failure, increased age, and those not exposed to beta-blockers were other independent risk factors for hospital mortality. Note, overall mortality was unchanged between groups (see manuscript text). CI = confidence interval.