<story><title>Scientists Edge Closer To Lab Test For Chronic Fatigue Syndrome</title><url>http://www.npr.org/sections/health-shots/2017/07/31/540565526/scientists-edge-closer-to-elusive-lab-test-for-chronic-fatigue-syndrome</url></story><parent_chain><item><author>Gibbon1</author><text>The thing that currently spazs me out is the Simpson Paradox (Yule–Simpson effect)&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Simpson%27s_paradox&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Simpson%27s_paradox&lt;/a&gt;&lt;p&gt;In short, if your population has two (or more) diseases with similar enough symptoms that they are grouped together, statistical analysis can and does totally fail. And your experiment will produce garbage.&lt;p&gt;So what if Chronic Fatigue Syndrome is really caused by a couple of different things, but with converging symptomology. You have a real catch 22 situation. Can&amp;#x27;t identify the cause of the disease without a consistent experimental group. Can&amp;#x27;t select a consistent experimental group without a functional test.</text></item><item><author>kens</author><text>I looked at the paper and the data is kind of strange. Looking at figure 2, there are a bunch of cytokines that have a nice linear progression with increasing levels corresponding to increasing severity of disease. This seems like solid evidence that more cytokine = bad.&lt;p&gt;But if you compare with the controls, mild cases of ME&amp;#x2F;CFS have &lt;i&gt;less&lt;/i&gt; than the control, moderate cases have the same as controls, and severe cases have more. This kind of torpedoes any simple explanation of what&amp;#x27;s going on. The authors discuss this in a kind of hand-wavy way that maybe ME&amp;#x2F;CFS causes some down-regulation to start with and then the increasing trend is on top of that.&lt;p&gt;So, I&amp;#x27;m not sure what to make of this. It seems useless as a test at this point: &amp;quot;You have totally normal cytokine levels, indicating that you&amp;#x27;re either healthy or have moderate ME&amp;#x2F;CFS.&amp;quot;</text></item></parent_chain><comment><author>zik</author><text>Chronic Fatigue Syndrome is a syndrome - ie. &amp;quot;a group of symptoms which consistently occur together&amp;quot;. The fact that it&amp;#x27;s called a syndrome rather than a disease is a recognition that it&amp;#x27;s not understood and may be in fact a grouping of different diseases with similar symptoms.</text></comment>
<story><title>Scientists Edge Closer To Lab Test For Chronic Fatigue Syndrome</title><url>http://www.npr.org/sections/health-shots/2017/07/31/540565526/scientists-edge-closer-to-elusive-lab-test-for-chronic-fatigue-syndrome</url></story><parent_chain><item><author>Gibbon1</author><text>The thing that currently spazs me out is the Simpson Paradox (Yule–Simpson effect)&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Simpson%27s_paradox&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Simpson%27s_paradox&lt;/a&gt;&lt;p&gt;In short, if your population has two (or more) diseases with similar enough symptoms that they are grouped together, statistical analysis can and does totally fail. And your experiment will produce garbage.&lt;p&gt;So what if Chronic Fatigue Syndrome is really caused by a couple of different things, but with converging symptomology. You have a real catch 22 situation. Can&amp;#x27;t identify the cause of the disease without a consistent experimental group. Can&amp;#x27;t select a consistent experimental group without a functional test.</text></item><item><author>kens</author><text>I looked at the paper and the data is kind of strange. Looking at figure 2, there are a bunch of cytokines that have a nice linear progression with increasing levels corresponding to increasing severity of disease. This seems like solid evidence that more cytokine = bad.&lt;p&gt;But if you compare with the controls, mild cases of ME&amp;#x2F;CFS have &lt;i&gt;less&lt;/i&gt; than the control, moderate cases have the same as controls, and severe cases have more. This kind of torpedoes any simple explanation of what&amp;#x27;s going on. The authors discuss this in a kind of hand-wavy way that maybe ME&amp;#x2F;CFS causes some down-regulation to start with and then the increasing trend is on top of that.&lt;p&gt;So, I&amp;#x27;m not sure what to make of this. It seems useless as a test at this point: &amp;quot;You have totally normal cytokine levels, indicating that you&amp;#x27;re either healthy or have moderate ME&amp;#x2F;CFS.&amp;quot;</text></item></parent_chain><comment><author>kens</author><text>That&amp;#x27;s a very good point. The paper suggests that &amp;quot;severity may be a key variable for subgrouping ME&amp;#x2F;CFS.&amp;quot;  So it&amp;#x27;s possible that there are three different ME&amp;#x2F;CFS diseases that can be distinguished by cytokine levels. Hopefully once these are separated, statistical analysis will succeed and medical progress would follow.&lt;p&gt;In the bigger picture, you have to wonder how many things that we currently categorize as one disease are really many different diseases. (Like how in the 1800s, people would die of &amp;quot;a fever&amp;quot; but we now know there are many different diseases causing fevers.) It&amp;#x27;s kind of a cliche now that cancer is not a single disease. I expect conditions such as autism and schizophrenia will fragment once the right tests are available. What else?</text></comment>