+ Cox regression analysis of the S2 case-cohort in: crude model, model without CRP, model with CRP with metabolite as continuous and categorical data respectively.
+ Association with CRP in the case cohort dataset.
+ nested case-control analysis in S2 case-cohort

#todo:
1. added predictive value with plots
2. S4 estimation with non-fasting samples: interaction with fasting status.
Merge branch 'Myocardial' of https://github.com/xutaosjtu/CVD into Myocardial
+ using weighted model estimation