by revere, cross-posted from Effect Measure

Since I talk a lot about flu in my real life as well as on the blog, I get questions from moms and care givers who wonder when they should start to get worried about a sick child or relative. It’s context dependent, of course. The same symptoms that would be shrugged off at any other time take on a different meaning during a flu outbreak, especially when everyone seems uncertain about what is happening or what might happen. There’s nothing irrational about this. Infection with influenza virus is always potentially serious and when the young and healthy are in the cross-hairs even more so. Many other viruses can cause the same initial symptoms (“flu-like symptoms”), outside of flu outbreaks the likelihood those symptoms represent influenza infections is small. When flu is circulating in the community, however, the likelihood that the very same symptoms are from an influenza infection goes way up (the reasons can be found via an elementary application of Bayes Theorem in probability theory). So knowing when things are going sour is more important.

The question came up at one of CDC’s press briefings last week, and CDC’s answer seemed to me quite helpful, so I retrieved it from the transcript of the presser for posting here. The context is the extra risk from swine flu infection (or any flu, for that matter) for those with “underlying medical conditions.” There are two questions here. The first related to what constituted an underlying medical condition. Some of the examples cited seemed quite common (asthma, COPD, pregnancy), so much so that a large proportion of the population might be considered to have an underlying condition. So CDC’s Dr. Schuchat addressed the question of warning signs that indicate the person should seek immediate medical attention.

In children, signs that need urgent medical attention include fast breathing or trouble breathing; blueish or gray skin color; not drinking enough fluids; severe, persistent vomiting; not waking up or not interacting.; being so irritable that the child doesn’t want to be held; and flu-like symptoms improve, but then return later with a fever and a worse cough. Those are warning signs we physicians think about all the time, with respiratory infections. And they’re good to have in mind with this new influenza-like illness caused by the novel H1N1 strain. Just good things for parents to have in the back of their mind.In adults, we look at another set of warning signs that suggest the need for urgent medical attention: difficulty breathing or shortness of breath; pain or pressure in the chest or abdomen; sudden dizziness, confusion, persistent or severe vomiting that doesn’t go away; and flu-like symptoms that improve, but then come back again with a fever or worsening of cough. (Statement by Dr. Anne Schuchat, CDC Press Briefing, May 28, 2009)

 Once again, I think this is pretty good messaging. It tells many people exactly what they want to know: when should I start to get worried? Anybody who has had to deal with these questions appreciates the difficulty. You don’t want to falsely minimize something that later could turn out to be serious, but you don’t want to cause people to do things that burden the system when it’s not necessary. The best thing is usually to provide the best information you have. Most people then act rationally and responsibly.

I confess to be both surprised and impressed at how well CDC has handled this. We’ve had 8 years where CDC’s credibility was spiraling down the toilet faster than you can say Bush Administration. How well the same leadership would have acquitted themselves in this swine flu outbreak we’ll never know. But the new one, under Acting Director Dr. Richard Besser, has done an impressive job. If this continues under the new Director, Dr. Thomas Frieden, CDC well be on the road back to health. It couldn’t happen at a better time.