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Is hazard ratio the same as incidence rate ratio?
The hazard ratio (HR) is the main, and often the only, effect measure reported in many epidemiologic studies. For all practical purposes, hazards can be thought of as incidence rates and thus the HR can be roughly interpreted as the incidence rate ratio.
What does a hazard ratio represent?
The hazard ratio is an estimate of the ratio of the hazard rate in the treated versus the control group. The hazard rate is the probability that if the event in question has not already occurred, it will occur in the next time interval, divided by the length of that interval.
How is hazard ratio related to relative risk?
Hazard ratio can be considered as an estimate of relative risk, which is the risk of an event (or of developing a disease) relative to exposure. Relative risk is a ratio of the probability of the event occurring in the exposed group versus the control (non-exposed) group.
How is the hazard ratio used in survival analysis?
The hazard ratio in survival analysis is the effect of an exploratory? variable on the hazard or risk of an event. Hazard ratio can be considered as an estimate of relative risk, which is the risk of an event (or of developing a disease) relative to exposure.
When does a hazard ratio become a meaningless statistic?
Hazard ratios become meaningless when this assumption of proportionality is not met. If the proportional hazard assumption holds, a hazard ratio of one means equivalence in the hazard rate of the two groups, whereas a hazard ratio other than one indicates difference in hazard rates between groups.
How is the hazard ratio related to confidence interval?
Relative risk is a ratio of the probability of the event occurring in the exposed group versus the control (non-exposed) group. A confidence interval is an interval estimate of a population parameter. Instead of estimating the parameter by a single value, an interval of likely estimates is given.