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Obsidian | Level 7

## How to calculate person years in Cox regression?

Hi all,

I hope you are doing well. I am trying to calculate person years. I am not sure if there is any code we can use in proc phreg to get person year and number of events directly.

I also have another question. I selected participants who did not have health outcome and try to calculate person year by hand. I was wondering if there is any code I can use to get the sum of each product of each column* time: h:persist good person time=2*176+4*340+6*272+.......

Table of time by hear_p4cat
time hear_p4cat
h:persist good h:poor to good h:good to poor h:persist poor Total
2
 176
 25
 18
 19
 238
4
 340
 29
 39
 68
 476
6
 272
 37
 33
 51
 393
8
 319
 21
 33
 36
 409
10
 229
 22
 26
 30
 307
12
 247
 24
 17
 31
 319
14
 1275
 63
 79
 143
 1560
Total
 2858
 221
 245
 378
 3702

Thanks!

1 REPLY 1
Super User

## Re: How to calculate person years in Cox regression?

Please provide example data in the form of data step code. Instructions here: https://communities.sas.com/t5/SAS-Communities-Library/How-to-create-a-data-step-version-of-your-dat... will show how to turn an existing SAS data set into data step code that can be pasted into a forum code box using the </> icon or attached as text to show exactly what you have and that we can test code against.

If you can't manage that at least post the example as simple text in a text box. That particular tabular layout is not worth trying to write a data step with.

My first thought would be Proc Means/ summary with your Time variable as a Weight variable and then request a Sum for the other variables. DO not include the Total row, if you have such in your actual data set, as it is obviously not a numeric variable and a Weight variable must be numeric.

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