I'm a medical student.

I am working on some medical research. Given 3 values (BMI, age, gender) I have a list of baseline risks for the probability of an adverse event occurring in the next 10 years for an individual with a given BMI, age, gender.

I also have a list of additional risk factors, given as Hazard Ratios. How can I properly compute the 10-year probability of an adverse event, by modifying the baseline risk if say, 1 or more risk factors apply to an individual.

So, for example: given that an individual with age 30, gender Male, BMI 25 has a 5% risk of adverse event in next 10-years, assume some additional risk factors X and Y, which have respective HRs of 1.3 and 1.6, how can I modify the 5% risk to encompass the risk factors? I know that the HRs were computed using multivariable Cox proportional hazards for a 10 year period, with death considered as a competing hazard.

Any additional statistical wisdom would be appreciated.