Friday, 27 February 2009

Grow your own drugs

No, not the good kind, there is a new TV series being heavily trailed, by that title:

...James Wong, a 27-year-old ethnobotanist (a scientist who studies how people use plants), wants to change our minds. He passionately believes that safe, natural remedies can be made from the everyday plants you find in hedgerows, the back garden or local garden centres.

...In Malaysia, where Wong grew up, everyone treated themselves with natural remedies. Food, too, was used as medicine...

The problem, Wong believes, is that there's a big cultural dividing line between conventional medicine, which is thought of as effective, proven and serious, and herbal medicine, which has the reputation of being a bit flaky.

But, as Wong says, up to 50 per cent of over-the-counter medicines are based on chemicals that were first isolated from plants. "Aspirin, for example, is made from the same chemicals that were first isolated from willow, which has been used for thousands of years as a painkiller.

...Wong, who trained at the Royal Botanical Gardens at Kew, is quick to point out that the herbs and plants he recommends all have a long history of use and no record of toxicity.

So, presumably aspirin, which is derived from plants after all, has 'no record of toxicity'? This doesn't bode well.

Working women almost certainly caused the credit crunch

This is a brilliant article from the Irish Times:

Of course there will always be a place in the world of business for exceptional women. Women also have an important role to play in jobs that are too demeaning for men, like teaching. But the general employment of women is another matter. Indeed, working women almost certainly caused the credit crunch by bringing a second income into the average household, pushing property prices up to unsustainable levels.

Whether working women actually caused the credit crunch is now a moot point. The point is that removing women from the workforce would mitigate its effects.

...

It would be ludicrous to suggest that women should be sacked purely to give men their jobs. In many cases, their jobs should be abolished as well.

Wednesday, 25 February 2009

A Million Women Drinking

Some data from the Million Women Study (of women aged over 50) has caused some headlines today:

A glass of wine each evening is enough to increase your risk of developing cancer, women are being warned.
Consuming just one drink a day causes an extra 7,000 cancer cases - mostly breast cancer - in UK women each year, Cancer Research UK scientists say.
These reports are based on this study and press release. I've graphed some of their data (top right, 95% floated** CI). I think it is clear that the difference between a drink a day and less than 2 drinks a week (this was the reference group because non-drinkers often includes ex-alcoholics or those who have given up because they are already sick) is less than convincing (obviously it is difficult to interpret given that both the upper end of the 3-6u group and the lower end of the 7-14u group cover around 1u/day).

The claim that "each additional drink regularly consumed per day may account for approximately 15 excess cancers per 1000 women up to age 75" is actually based on a regression on the average amount of alcohol consumed in each category* - this data is represented in the middle right graph (as above but with mean alcohol, a regression line, excluding non-drinkers, and 95% CI). We can see that average consumption in neither group is conveniently near an average consumption of 1 drink (10g)/day.

It is clear that the regression is strongly driven by the heaviest alcohol consuming group, with a shallower regression being indicated if you exclude these subjects, and this highlights the limits of doing a regression analysis and then reporting the increased risks per unit of alcohol, since any non-linearity can make the linear regression coefficients misleading (such that while the regression line may describe a Y% risk for every X units, the data may still not support a statistically significant Y% increase for the first X units drunk).

It is always worth being circumspect when dealing with epidemiological data that produces very small risks, because we cannot know that every confounding variable has been accounted for in what is simply an observational study. Look at the zero alcohol consumption group (this would not actually be zero since 7% of these were actually drinking alcohol by the 3-year followup, but they don't provide the mean data), looks like there is something different between these individuals and those with minimal alcohol consumption - but this is not captured in the data (the relative risks have already been adjusted for available confounding variables).

I'm not sure why my estimates of additional risk per 10g/day are so much less than the study (obviously my regression is Mickey Mouse but it fits nicely, and it doesn't seem to be due to me not using log-linear regression either) - I get less than 1.05 relative risk (as you can see from the graph), their estimate of 15 additional deaths per 1000 women is around a 1.13 relative risk, although it appears that they are only include those cancers with an increased risk from alcohol associated with them, i.e. they don't include the lives saved by alcohol preventing lymphoma, thyroid, and kidney cancer!

If we look at the figures they report in the study, they say that there is an incidence of 118 cases of cancers that alcohol increases the risk for (oropharynx, oesophagus, larynx, rectum, liver, breast) per 1000 women up to age 75 years, and by drinking 10u/day this risk is up to 133 per 1000 women (which is where I got the 1.13 relative risk from)***. Since these cancers made up around half of those in this study we could estimate that the overall cancer risk for women up to 75 years is 236 per 1000, applying our approximate overall increase in cancer risk of 1.05 we get an extra 12 cancers per 1000 women, or an increase in absolute risk of cancer of 1.2% - that is, drinking 10u/day means that the chances of you getting cancer before you are 75, which is 24% anyway, goes up by another 1.2%.

Interestingly the data suggest that the increased risk in cancers of the upper aerodigestive tract (larynx, oropharynx, oesophagus), which are some of the cancers increased in incidence with alcohol consumption in this study (the others being liver, rectum and breast cancer), is due to a synergistic effect with smoking tobacco (see their figure 4 - bottom right) - and this may mean the study overstimates the risk of alcohol - or rather, it fails to highlight that some of the apparent additional risk of alcohol only applies if you also smoke (it would be possible to control for this using covariates if smokers and non-smokers were modelled seperately).


* A unit is 8g alcohol, nowadays many wines and beers a sufficiently strong that they contain 10g per serving (small glass, half a pint) and this study uses 'a drink' to mean 10g alcohol.

** These confidence intervals are based on a 'floating absolute risk' model which is controversial and results in narrower CIs than conventional techniques.

***This is dodgy, to multiply the 118 cases of cancer by the estimated relative risk at 10u/day of 1.13 (which is what they seem to be doing) would only be valid if the 118 cases was from women in the lowest risk group - those drinking <= 2u/week - but we know that many women do drink more than this (nearly half in this study), and the overall cancer rate therefore already includes this extra alcohol related risk. However, if I adjust my above figures to account for this it doesn't make much difference - giving an additional 11 cancer per 1000 women, and thus absolute increased risk of 1.1%.

Tuesday, 24 February 2009

Grandma

In these challenging times it is good to see unveiled a £2m state funded memorial to an unelected woman paid millions of pounds by the British taxpayer, and whose surviving family consists of further unelected state funded multimillionaires.

Her grandson said:
At long last my grandparents are reunited in this joint symbol, which in particular reminds us of all they stood for and meant to so many during the darkest days this country has ever faced

At long last indeed, perhaps he could have chipped in, got it speeded up, he could probably spare a few quid.

Monday, 16 February 2009

Friday, 13 February 2009

Bankrupt

I can't understand why this song has not got more airplay as background music for news reports given the current climate:



This is from "9 Red Songs" (from 2005, so prescient) by Chris T-T, I also recommend "The Huntsman Comes A-Marchin'" and "Preaching to the Converted".

Johann Hari on free speech

Writing in the Independent:

Last week, I wrote an article defending free speech for everyone – and in response there have been riots, death threats, and the arrest of an editor who published the article.
Read it all.