n>
</div><div class='output co'>#&gt; [1] FALSE
#&gt; attr(,"msg")
#&gt; [1] "DS is missing the variable: DSSTDTC"</div><div class='input'>
<span class='va'>AE1</span> <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/r/base/data.frame.html'>data.frame</a></span><span class='op'>(</span>USUBJID <span class='op'>=</span> <span class='fl'>1</span>,
                  AEDTHDTC <span class='op'>=</span> <span class='st'>""</span>,
                  AESTDTC <span class='op'>=</span> <span cl