[R] Summarising Data for Forrest Plots

[Polwart Calum (County Durham and Darlington NHS Foundation Trust)]

> Are n.FD and n.RD the number of people who received the full/reduced dose
Yes - but I don't have the data structured like that YET - thats what I want to get to because thats what forest plot seems to be wanting.

> and surv.FD and surv.RD the number of people that survived?
Mmm... was more thinking of something like median survival?  ALthough the brain hasn't kicked into gear yet tonight and it might actually be mean to be a hazard ratio?

>And are the people who received the full dose different from the people who received the reduced dose?
Yes

> And what exactly is it that you want to plot in the forest plot?
Subgroups - see below

>From the way you have arranged the table, it seems as if you want some kind of effect size measure that contrasts the survival rate of the full versus reduced dose in the various subgroups. Is that correct?
Yip that sounds right

>And are you just trying to figure out how to draw the forest plot once you have the data in the table form as shown in your post or are you also trying to figure out how to create that table to begin with?
I *think* I can draw the plot once I have the data structured right.  But at the moment my data is structured like this:

PatientID  FullDose   Survival  Censored  Age     Sex   Normal Renal Func   Grade of Toxicity

001          Y                125         N               75       F       Y                                 1
002          N                55           Y               55       M      N                                 4
003          N                65          Y                78       F       Y                                 2

I want to eventually get to a forest plot that looks a bit like this:

Age:
< 65                            |-------------#---------------|----|
>= 65         |-------------#----------------|               |
                                                                           |
Sex:                                                                    |
M                                                            |-----#--|---|
F      |---------------#---------------------|               |
                                                                           |
Renal Fucn:                                                       |
Normal                       |---------------#-------------|
Abnormal                   |---------------#-------------|
                                                                           |
Grade of Toxicity:                                              |
0-1                                                                     |  |-------#-------|
2                                      |-----#------|                |
3-4          |----------#------------|                          |
                                                                          |
Overall:                                          <>               |


Which I believe I can achieve using the metaplot or forrest plot functions, replacing the studies with the relevant sub groups.  But my challenge has been converting the patient data above down to list subgroups.  Other than by running a survival analysis individually on an individual subgroup recording the results and building up a table.

Calum

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