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From | Marcos Vinicius <bioestatistico@inbox.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: KM curve adjusted by the Inverse Probability of Treatment Weights(IPTW) |
Date | Thu, 20 Dec 2012 08:55:11 -0800 |
Hello, I would like to generate a Kaplan Meier curve adjusted(controlled/corrected) by the Inverse Probability of Treatment Weights(IPTW). Supose I have a dataset with columns: tx=treatment (0/1) , ps=propensity score weig= Inverse Probability of Treatment Weights (iptw),time (=survival time)remission(1/0) (0=censored), In IPTW, individuals are weighted by the inverse probability of receiving the treatment that they actually received. In SAS I tried this code but it is not working although it is indicated in the SAS/STAT 12.1 User’s Guide The LIFETEST Procedure (Chapter) Someone could help me with a Stata code to produte and compare 2 Km curves according to treatment group but adjusted by iptw(weig) proc lifetest method=km data=ps plots = (survival ); time time*remission(0); weight weig; survival out=surv_data conftype=loglog ; /*weight weig;*/ ODS EXCLUDE ProductLimitEstimates Means LogrankHomCov WILHOMCOV HomStats TaroneHomCov PetoHomCov Rank HomTests ; /*weight weig;*/ strata tx; /*weight weig;*/ run; [ Error message from SAS log ERROR 180-322: Statement is not valid or it is used out of proper order. After program the propensity score weight , also referred to as the inverse probability oftreatment weight (IPTW)( weig in the SAS code) I tried to use the weight statatement from proc Lifetest to produce a Kaplan-Meier curve adjusted by iptw. It is not working. Someone could help me in the code implementation or guide another way to produce the KM curve adjusted by propensity score?: Many thanks, Vinicius. ____________________________________________________________ GET FREE SMILEYS FOR YOUR IM & EMAIL - Learn more at http://www.inbox.com/smileys Works with AIM®, MSN® Messenger, Yahoo!® Messenger, ICQ®, Google Talk™ and most webmails * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/