Antioxidant treatment to reduce mortality and serious adverse events in adult surgical patients: A systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Hyperoxia during anesthesia can increase cellular oxidative stress, and perioperative antioxidant treatment may reduce the resulting damage. The aim of this review was to evaluate risks and benefits of antioxidant treatment in surgical patients. We hypothesized that antioxidant treatment reduced mortality compared to placebo/no intervention.

METHODS

This systematic review with meta-analyses and trial sequential analysis (TSA) was conducted using Cochrane standards and GRADE methodology. Randomized clinical trials comparing perioperative antioxidant treatment vs. placebo/no intervention in adults were included. Primary outcome was mortality at longest follow-up.

RESULTS

Ninety-seven trials with 8156 patients were included. The most common interventions were N-Acetylcysteine (36 trials) and vitamin C (29 trials). Trials were primarily performed during cardiac surgery (53 trials). Fifty-six trials with 4890 patients reported information on mortality (243 events). The meta-analysis of mortality at longest follow-up showed a reduced mortality in antioxidant treated patients (RR 0.74, 95% CI 0.59; 0.94, I2 0%), however, TSA-adjusted CI was broadened (0.55-1.02) and only 31% of the required information size was reached. Furthermore, in the subgroup of three trials with overall low risk of bias the RR for mortality was 1.18 (95% CI 0.39, 3.63). Based on GRADE, our findings are of low quality of evidence due to high risk of bias, imprecision, and indirectness.

CONCLUSION

We found a 26% relative risk reduction of mortality in surgical patients treated with antioxidants but the quality of evidence supporting our findings is low and influenced by clinical heterogeneity and high risk of systematic- and random errors.

Hydroxyethyl starch 130/0.42 versus Ringer's acetate in severe sepsis

BACKGROUND

Hydroxyethyl starch (HES) [corrected] is widely used for fluid resuscitation in intensive care units (ICUs), but its safety and efficacy have not been established in patients with severe sepsis.

METHODS

In this multicenter, parallel-group, blinded trial, we randomly assigned patients with severe sepsis to fluid resuscitation in the ICU with either 6% HES 130/0.42 (Tetraspan) or Ringer's acetate at a dose of up to 33 ml per kilogram of ideal body weight per day. The primary outcome measure was either death or end-stage kidney failure (dependence on dialysis) at 90 days after randomization.

RESULTS

Of the 804 patients who underwent randomization, 798 were included in the modified intention-to-treat population. The two intervention groups had similar baseline characteristics. At 90 days after randomization, 201 of 398 patients (51%) assigned to HES 130/0.42 had died, as compared with 172 of 400 patients (43%) assigned to Ringer's acetate (relative risk, 1.17; 95% confidence interval [CI], 1.01 to 1.36; P=0.03); 1 patient in each group had end-stage kidney failure. In the 90-day period, 87 patients (22%) assigned to HES 130/0.42 were treated with renal-replacement therapy versus 65 patients (16%) assigned to Ringer's acetate (relative risk, 1.35; 95% CI, 1.01 to 1.80; P=0.04), and 38 patients (10%) and 25 patients (6%), respectively, had severe bleeding (relative risk, 1.52; 95% CI, 0.94 to 2.48; P=0.09). The results were supported by multivariate analyses, with adjustment for known risk factors for death or acute kidney injury at baseline.

CONCLUSIONS

Patients with severe sepsis assigned to fluid resuscitation with HES 130/0.42 had an increased risk of death at day 90 and were more likely to require renal-replacement therapy, as compared with those receiving Ringer's acetate. (Funded by the Danish Research Council and others; 6S ClinicalTrials.gov number, NCT00962156.).