David Thank you for your thoughts. The data I am analyzing do not come from a clinical trial but rather from a cohort study whose aim is to determine risk factors for surgical therapy to treat their joints. John
Sent from my iPhone On Jul 25, 2013, at 9:15 PM, "Marc Schwartz <marc_schwa...@me.com>" <marc_schwa...@me.com> wrote: > > On Jul 25, 2013, at 4:45 PM, David Winsemius <dwinsem...@comcast.net> wrote: > >> >> On Jul 25, 2013, at 12:27 PM, Marc Schwartz wrote: >> >>> >>> On Jul 25, 2013, at 2:11 PM, John Sorkin <jsor...@grecc.umaryland.edu> >>> wrote: >>> >>>> Colleagues, >>>> Is there any R package that will allow one to perform a repeated measures >>>> Cox Proportional Hazards regression? I don't think coxph is set up to >>>> handle this type of problem, but I would be happy to know that I am not >>>> correct. >>>> I am doing a study of time to hip joint replacement. As each person has >>>> two hips, a given person can appear in the dataset twice, once for the >>>> left hip and once for the right hip, and I need to account for the >>>> correlation of data from a single individual. >>>> Thank you, >>>> John >>> >>> >>> >>> John, >>> >>> See Terry's 'coxme' package: >>> >>> http://cran.r-project.org/web/packages/coxme/index.html >> >> When I looked over the description of coxme, I was concerned it was not >> really designed with this in mind. Looking at Therneau and Grambsch, I >> thought section 8.4.2 in the 'Multiple Events per Subject' Chapter fit the >> analysis question well. There they compared the use of coxph( >> ...+cluster(ID),,...) withcoxph( ...+strata(ID),,...). Unfortunately I >> could not tell for sure which one was being described as superio but I think >> it was the cluster() alternative. I seem to remember there are discussions >> in the archives. > > > David, > > I think that you raise a good point. The example in the book (I had to wait > to get home to read it) is potentially different however, in that the > subject's eye's were randomized to treatment or control, which would seem to > suggest comparable baseline characteristics for each pair of eyes, as well as > an active intervention on one side where a difference in treatment effect > between each eye is being analyzed. > > It is not clear from John's description above if there is one hip that will > be treated versus one as a control and whether the extent of disease at > baseline is similar in each pair of hips. Presumably the timing of hip > replacements will be staggered at some level, even if there is comparable > disease, simply due to post-op recovery time and surgical risk. In cases > where the disease between each hip is materially different, that would be > another factor to consider, however I would defer to orthopaedic > physicians/surgeons from a subject matter expertise consideration. It is > possible that the bilateral hip replacement data might be more of a parallel > to bilateral breast cancer data, if each breast were to be tracked separately. > > I have cc'd Terry here, hoping that he might jump in and offer some insights > into the pros/cons of using coxme versus coxph with either a cluster or > strata based approach, or perhaps even a frailty based approach as in 9.4.1 > in the book. > > Regards, > > Marc > > >> >> -- >> David. >>> >>> You also might find the following of interest: >>> >>> http://bjo.bmj.com/content/71/9/645.full.pdf >>> >>> http://www.ncbi.nlm.nih.gov/pubmed/22226885 >>> >>> http://www.ncbi.nlm.nih.gov/pubmed/22078901 >>> >>> >>> >>> Regards, >>> >>> Marc Schwartz >>> >>> ______________________________________________ >>> R-help@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >> >> David Winsemius >> Alameda, CA, USA >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > Confidentiality Statement: This email message, including any attachments, is for th...{{dropped:6}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
