Centers for Disease Control–go to the source

Med Pundit recently wrote about the current media fed Flu Scare, and without picking on him too much, I’ll just say that he mentions some very scary statistics in his post regarding the mortality rate of influenza this year. I had to reread the paragraph twice to be sure that doubts were correct. Further down the page, he corrects his mistakes in an editorial update.

What lesson can be learned here? Always go to the source…it’s how I learn best. After reading the essay at medpundit, I needed to understand the following excerpt:

The proportion of deaths attributed to pneumonia and influenza was 6.5%, which is below the epidemic threshold for the week.

and his interpretation:

I read that to mean that the death rate is about the same or lower than usual.

Had he gone to the source, (which he came close to with this patient centered page about the the flu), and scrolled down to the double asterixed footnote, he would have found the following explanation (from MMWR or Morbidity and Mortality Weekly Report):

** The expected baseline proportion of P&I deaths reported by the 122 Cities Mortality Reporting System is projected by using a robust regression procedure that applies a periodic regression model to the observed percentage of deaths from P&I during the previous 5 years; the epidemic threshold is 1.645 standard deviations above the seasonal baseline percentage (2).

And finally, clicking on the (2) reference at the end of the footnote would have led him to the source of information for the “epidemic threshold” mentioned in the original post. From which the following data is abstracted:

During each October–May in the period covered, CDC received weekly reports from 1) approximately 120 World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories in the United States regarding influenza virus isolations; Throughout the year, the vital statistics offices in 122 cities reported weekly on deaths related to pneumonia and influenza (P&I).

We’ve finally gotten to the roots of the data Medpundit originally pontificated upon. I won’t analyze the numbers, if you’re interested, you can dive into all of it yourself. I thought this was a good opportunity to highlight the importance of going to the source and not relying on a third (or fourth or fifth) party to intepret it for you.

The CDC is an amazing resource for scientific as well as consumer oriented information on just about any disease you can imagine. It is well worth browsing if you’ve never done so.

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