Hmmm. I skim the article and I guess we need to start with the basics. There is a meta-analysis that was conducted using proportional hazards regression controlling for age and sex that found for ever standard deviation of stiffness (defined as z-score of logetransformed aPWV) above the population mean, risk for cvd went up 45%. OK that is straightforward.

Now the confusion, what are you trying to do? Replicate their study just using your own data, just calculate RR given your data, or are you trying to merge your data with their results. If so, why. I can quite follow your actions.