What is risk?

Titrated oxygen was compared with the standard treatment of high flow oxygen for patients with acute exacerbation of chronic obstructive pulmonary disease in the pre-hospital setting. A cluster, randomised controlled, parallel group trial was performed. In total, 405 patients with a presumed acute exacerbation of chronic obstructive pulmonary disease that had been treated by paramedics and who had been transported and admitted to hospital were included. A total of 226 patients were randomised to high flow oxygen and 179 to titrated oxygen. The main outcome measure was mortality, either pre-hospital or in-hospital mortality.1

The risk of mortality in patients randomised to titrated oxygen treatment was less than that in the patients randomised to high flow oxygen (seven deaths (3.9% of patients) versus 21 deaths (9.3%)). The researchers concluded that titrated oxygen treatment significantly reduced mortality in comparison with high flow oxygen in acute exacerbations of chronic obstructive pulmonary disease (relative risk 0.42 (95% confidence interval 0.2 to 0.89; P=0.02)).

Which of the following statements, if any, are true?

• a) The …