Contributor
Posts: 27

# How to calculate difference of cholesterol level between 3 time points?

I have 100 patients in my dataset. We collected cholesterol level at 3 time points during their visits to the hospital (visit=1, 2, 3). I would like to get the differences of cholesterol (1) between visit 1 and visit 2, and (2) between visit 3 and visit 1.

data looks like this:

ID            Visit      Cholesterol level

001          1           100

001          2           120

001          3           130

002          1           200

002          2           220

002          3           250

003          1           80

003          2           90

003          3           85

How to I get Cholesterol_diff1 and Cholesterol_diff2?

Cholesterol_diff1 = cholesterol2-chlesterol1;

Cholesterol_diff2 = cholesterol3-chlesterol1;

Super User
Posts: 23,776

## Re: How to calculate difference of cholesterol level between 3 time points?

Look at the DIF<n>() function which can calculate multiple DIF values.

ie

data class;

set sashelp.class;

x =dif(age);

y=dif2(age);

run;

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