What Cox proportional hazard is
Cox Proportional Hazards (CPH) is a statistical method used to analyse the effects of risk factors on the time to an event. It is a type of survival analysis, where the event of interest is death or the occurrence of some other event. It is used to determine the relative risk of an event occurring over a given period of time.
The steps for conducting a Cox Proportional Hazards analysis are as follows:
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Gather the data: Collect data on the event of interest (e.g. death) and the risk factors associated with it.
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Estimate the baseline hazard: Estimate the baseline hazard (the risk of the event occurring in the absence of any risk factors) using a parametric or non-parametric method.
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Estimate the coefficients: Estimate the coefficients for each of the risk factors using the Cox Proportional Hazards regression model.
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Calculate the risk: Calculate the risk of the event occurring for each subject given the risk factors present.
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Evaluate the results: Evaluate the results to determine if the risk factors are associated with the event.
Examples
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Cox proportional hazard can be used to assess the impact of a particular factor on the risk of experiencing a particular event, such as death, over time.
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Cox proportional hazard can be used to determine the relative risk of an event given a certain set of factors, such as age, gender, or lifestyle.
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Cox proportional hazard can be used to compare the efficacy of different treatments or interventions in reducing the risk of a particular event.
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Cox proportional hazard can be used to evaluate the impact of time-varying factors on risk over time.
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Cox proportional hazard can be used to determine the impact of an intervention on the rate of an event over time.