Definition Of Hazard Ratio In Clinical Trials

A hazard ratio of 1 0 indicates that the variable has no impact on the outcome.

Definition of hazard ratio in clinical trials. While more than one drug dose was tested in two of the examples outcomes were similar and the statistics shown could apply to either curve. Regression models are used to obtain hazard ratios and their confidence intervals. The reported hazard ratios and relative risk ratios were both 3. The instantaneous hazard rate is the limit of the number of events per unit time divided by the number at risk as the time interval approaches 0.

A hazard ratio of less than 1 0 indicates that the variable decreases the likelihood of the outcome. While a hazard ratio is similar to a relative risk ratio it isn t exactly the same. Let s say a clinical trial investigated survival rates for two drugs a and b. The hazard ratio is the ratio of chance of an event occurring in the treatment arm chance of an event occurring in the control arm 20 the hr has also been defined as the ratio of risk of outcome in one group risk of outcome in another group occurring at a given interval of time 21.

Where n t is the number at risk at the beginning of an interval a hazard is the probability that a patient fails between. In biostatistics the calculated likelihood that a particular intervention will make a study outcome more or less likely to occur.