Hazard ratios, which are often abbreviated HR, are one way researchers report the relative effect of a drug, treatment, or exposure. A hazard ratio of 1 indicates no effect of an exposure or treatment. Hazard ratios over 1 indicate increased risks. Hazard ratios under 1 indicate decreased risk. Hazard ratios are similar to, but not exactly the same as relative risks or risk ratios, though they are often reported the same way.
