espect to follow-up time).</p>
<div class="sourceCode" id="cb4"><pre class="sourceCode r"><code class="sourceCode r"><a class="sourceLine" id="cb4-1" title="1">aids<span class="op">$</span>CD4count &lt;-<span class="st"> </span>aids<span class="op">$</span>CD4 <span class="op">*</span><span class="st"> </span>aids<span class="op">$</span>CD4</a>
<a class="sourceLine" id="cb4-2" title="2">aids<span class="op">$</span>obstimef &lt;-<span class="st"> </span><span class="kw"><a href="https://www.rdocumentation.