SAS code for selecting lab value

[RM121]

Hi, 

I have eGFR data with multiple eGFR values per patient. And I want to select the eGFR value closest to diagnosis date (+-2 months). And for patients with multiple values in +-2 months period I want to select the eGFR value prior to diagnosis and closest to diagnosis date. I am not able to write the code for the "elect the eGFR value prior to diagnosis and closest to diagnosis ". Appreciate any help I can get. 

Here is the code I have so far:

data Y;
set X;
CalCreDiff=eGFRdate-DX_DATE;
AbsCaleGFRDiff=abs(CalCreDiff);
if -60<=AbseCaleGFRDiff=<60;
run;

[Jagadishkatam]

any sample data would help for better response

[ballardw]

The code you are attempting is about 2 lines longer than it needs to be. Unless you later that need one or more of the AbsCaleGFRDiff or CalCreDiff variables then do the arithmetic inside the ABS function.

Also you only need one side for the comparison.

data example;
   input x y;
   if abs(x - y) le 60 then put "Between -60 and 60";
   else put "Out of range";
datalines;
120  60
120  59
120  61
0   -61
0   -60
0   -59
;