Good afternoon,
I am trying to replicate the below methods, but I am lost on the SAS code/procedures needed to reproduce the bolded section. I have searched Google and chat rooms and other SAS sites for hours and have come up with half fixes every time or code that doesn't run. I am at a loss and now on a time crunch. Any assistance would be GREATLY appreciated. Thank you in advance.
"Two-thirds of the study participants (n ¼ 10,039) were randomly assigned to a derivation cohort for the development of risk prediction models with computer-generated random numbers, and the remaining one-third (n ¼ 5019) were reserved as an independent validation cohort. Among the patients allocated to the derivation cohort, new risk prediction models for all-cause and cardiovascular death were developed by using multivariable Cox proportional hazards models including the above-mentioned risk factors. In these models, survival analysis was censored at last date of follow-up or date of death. The performance of each risk prediction model was tested among either the patients assigned to the derivation or the validation cohort. The ability of each model to discriminate patients who died within 5 years from surviving patients was evaluated using the c-statistic for the survival analysis. Observed risk (based on the Kaplan-Meier product limit method) and predicted risk (based on the risk prediction model) of each outcome at 5 years were compared by ranking participants into deciles of predicted risk, and calibration of each model was evaluated in the derivation cohort using a modified Hosmer-Lemeshow c2-statistic with 9 degree of freedom. In addition, the risk prediction model for each outcome was translated into a simple score sheet in the same way as described in the Framingham Heart Study.22 All statistical analyses were performed with SAS 9.3 (SAS Institute, Cary, NC). Two-sided values of P < 0.05 were considered statistically significant."
Thank you!
