Mortality Increased With Liberal Oxygen Therapy in Acutely Ill Patients

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Liberal supplemental oxygen therapy in acutely ill patients increased mortality during hospitalization, at 30 days, and at longest follow-up.

Compared with conservative supplemental oxygen therapy, liberal supplemental oxygen therapy increased mortality during hospitalization, at 30 days, and at longest follow-up in acutely ill adults, according to the results of the IOTA (Improving Oxygen Therapy in Acute-Illness) study published in the Lancet.

Oxygen therapy is frequently administered to acutely ill individuals in an effort to prevent or reverse hypoxemia. However, between 50% and 84% of those who receive supplemental oxygen are exposed to excess oxygen and the potential for hyperoxemia.

Yet, many healthcare providers consider supplemental oxygen a harmless and potentially beneficial therapy despite the lack of strong evidence for this practice.

Derek K. Chu, MD, PhD, of the Department of Medicine at McMaster University in Hamilton, Ontario, Canada, and colleagues performed a systematic review and meta-analysis of studies identified using the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, HealthSTAR, LILACS, PapersFirst, and the WHO International Clinical Trials Registry. They included randomized clinical trials that compared liberal and conservative oxygen therapy in acutely ill adults from inception to October 25, 2017.

The investigators included 25 randomized trials with a total of 16,037 patients. The main outcomes were mortality and morbidity, which included disability at longest follow-up, risk for hospital-acquired pneumonia, any hospital-acquired infection, and length of hospital stay. They assessed these outcomes using random-effects meta-analyses.

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Liberal oxygen therapy increased the relative risk (RR) of in-hospital mortality (RR 1.21), 30-day mortality (RR 1.14), and longest follow-up (RR 1.10). All findings were high-quality evidence with an I2 of 0%. Furthermore, the liberal strategy failed to improve morbidity outcomes.

The authors suggested that supplemental oxygen might be detrimental above a saturation of peripheral oxygen range between 94% and 96% and concluded that oxygen therapy should be administered conservatively.


Chu DK, Kim LH-Y, Young PJ, et al. Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis. Lancet. 2018;391:1693-1705.