; [1] "There are 1 patients with a death date different in DS and AE. "
#&gt; attr(,"data")
#&gt;   USUBJID    DSSTDTC   AEDTHDTC RAVE.DS       RAVE.AE
#&gt; 3       3 2000-01-01 2020-01-03 XXX-R:0 FORMNAME-R:19</div><div class='input'>
<span class='co'># check for non existence of vars</span>
<span class='va'>DS</span><span class='op'>$</span><span class='va'>DSDECOD</span> <span class='op'>&lt;-</span> <span class='cn'>NULL</span>
<span class='va'>DS</span><span class='op'>$</span><span class='va'>DSSTDTC