Mortality

Here's a pair of medical terms I have often seen together. One of them I thought I had a moderately good understanding of the meaning, and the other I wasn't really sure exactly what it meant.

As with my previous post in this series, the same comment applies: If a medical doctor happens to read this and notices that I have something wrong, I would be thrilled to get a correction. I'm not a doctor and I'm writing this for other not-doctors; while I'm ok with simplification I don't want to be wrong.

Now, for my pair of terms: mortality is the former; it means how many people die. (Rather appropriate for a Hallowe'en post!) But it's also more than that; it is, specifically, the number of deaths in a given group over a given time period, and what the group and time period is has to be defined. The restrictions make sense, once I stopped to think about it: ultimately, the mortality of humans is 100% - everybody dies of something, at some point. But if you look at the mortality of a disease, or a type of accident, then the group is restricted to the people who have that disease or that injury, and the time is restricted to the time of the study, and the mortality is less than 100%. Something else kills the other people in the study at some other time, not covered by the study.

Research

I've been following the Science Based Medicine blog for a while now (even though I'm not a doctor) and one of the things I realized is that medical research is a whole lot more complicated than, say, chemistry. In the sort of trials I might do, if you put the same ingredients in a jar, you'll get the same results every time. In medical trials, this isn't the case, because human bodies are a whole lot more complicated than even a jar full of a hundred different chemicals. I sort of already knew this, but some of the articles on SBM have really made this clear to me.

Another thing I realized is that there is a lot of vocabulary around these trials which I only partially understood. So, here is my attempt at explaining this stuff more completely to myself. And, as it says in my sidebar, "I thought I'd share."

(If a medical doctor happens to read this and notices that I have something wrong, I would be thrilled to get a correction. I'm not a doctor and I'm writing this for other not-doctors; while I'm ok with simplification I don't want to be wrong.)

The first one I'm going to cover is clinical trials.

Biodegrading ... into what?

"Biodegradable" is one of many words commonly used to indicate something is environmentally friendly, but like many technical terms, it often doesn't mean the same thing in common usage as it does to a scientist. To me, "biodegradable" just means that the substance in question can be processed by some biological route into some other, usually lower molecular weight, substance.

It says nothing about the toxicity or harm—or benefit—that might be caused by the new substance.