Studying long

Looks like November wasn't a great month for posting, for me. Well, I'm back, and this time with another medical term. As with the others, if a medical doctor reads this and I'm wrong about something, I would love to hear about it so I can fix it. I am writing from a non-medical person's perspective for other non-medically trained people, but I hope I'm not making any doctors cringe.

So this time it's "longitudinal study". The basic idea behind a longitudinal study is that the study follows specific people for a long time—years, or decades. These can be used to tease out things like what affects aging or why some kids develop asthma but others don't, and many more.

Epidemiology circles back to sewage

Epidemiology, the statistical study of population health instead of a single person's health, has taken population-wide sampling to a new level—underground.

Instead of collecting data on individuals representing a subset of the population and then averaging it, the researchers let an existing piece of infrastructure do the averaging for them. This also made sure they were actually getting properly anonymized data from every single resident of the study area—because the area of study was "everybody connected to the sewer", and everybody who has one, uses the toilet.

What they were testing, specifically, was the percentage of people who took their medicine, by having the entire city collectively pee in a cup.

Useful blindness

I've run across the term "double-blind studies" in reference to medical research. In the operations and research that I've done myself, I've made use of "blind testing" as needed. It is widely considered both in medicine and in my own field of chemistry to be the most accurate way to get results uncontaminated by our own wishful thinking.

I wrote earlier about the placebo effect, and blinding the studies is probably the best way to counter it.

In chemistry, we really only need single blinding: the person running the lab tests doesn't know what the sample is supposed to be: a sample, a duplicate, a standard, or a blank. To do this, I hand over a set of sample bottles with nothing but code numbers written on them and tell them to test the lot for a particular set of compounds. A chemical reaction is a chemical reaction; if the same sample doesn't react the same way to the same test, it means somebody did something wrong somewhere along the way. In medicine, it's not so easy because there are patients involved, and their reactions (chemical, biological, and psychological) are all slightly different, and some of them will get better on their own no matter what is given to them.

A Tale of Two Studies

While looking up information on how ammonia takes the sting out of stings, I ran across two studies, both double-blinded, placebo-controlled trials of a sting relief formulation. The one that mentioned ammonia was the one I read first, because that's what I was looking for. The other one named a product brand name I'd never heard of before; I read it by accident, clicking on the wrong link in the search results. These two trials came up as the top two results when I searched google scholar for ammonia mosquito bite relief.

The two studies are: Effectiveness of Ammonium Solution in Relieving Type I Mosquito Bite Symptoms: A Double-blind, Placebo-controlled Study and The efficacy of Prrrikweg® gel in the treatment of insect bites: a double-blind, placebo-controlled clinical trial.

Go ahead and read only the abstract; those are all I'm going to talk about, not the rest of the papers. The abstracts say it all.

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.

New medicine from old

Traditional medicines can be interesting things. Some don't work at all despite being widely used, but some, like the bark and leaves of willow (Salix), work very well and have been effectively used for millennia—there are written records from 500 BC referring to its use. More recently (the 1820s) the active ingredient, salicylic acid, was produced, then in the 1890s acetylsalicylic acid, what we know as modern aspirin or ASA, was created. Aspirin no longer comes from plants as willow trees can't grow fast enough to sate the world's appetite for painkillers, but is now synthesized from phenols.

Another traditional painkiller, a milkwood (Tabernaemontana) has been under investigation for several years now. According to the studies, it contains a mixture of several things, including compounds in the class of opioids (a painkiller type which tends to have undesirable side effects and which causes addiction) and conolidine, among many others.

The conolidine and other compounds were isolated and identified in 2004, but conolidine couldn't be properly studied at that time because they only managed to get a 0.00014% yield when purifying it out of the plant. In May 2011, a team of researchers from the Scripps Research Institute announced that they had not only managed to synthesize conolidine, they had also tested it on mice and found out that it had painkiller effects as strong as morphine, but without any of morphine's adverse side effects.