In Contact - November 2005
Proof? Spoof?
Following the feedback surrounding Efron?s RGP predictions [See In Contact September and October ?05], I've had some further enlightening correspondence.
I discussed, in passing, the issues that continue to crop up regarding evidence based medicine and anecdotal, clinical observational reporting. One regular correspondent brought to my attention what has to be one of the best research papers I've ever read.
Thanks mate!
Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials by Smith and Pell appeared in the December 20th, 2003 edition of the BMJ (British Medical Journal).
It is in my opinion required reading and makes the very good point [in a suitably scientific manner] that we all know parachutes work - at a very high level of repeatability - without the need to perform randomised controlled trials.
Some of the headings are great. Take for example the following;
?Evidence based pride and observational prejudice? or ?the parachute and the healthy cohort effect?.
?Parachutes and the military industrial complex? was even funnier where the authors comment that large multinational manufacturers make billions of dollars selling parachutes based merely on a belief of the efficiency of their product.
They also make the following earth shattering deductions; if you?ll excuse the pun?
? No randomised controlled trials of parachute use have been undertaken.
? The basis for parachute use is purely observational, and its apparent efficacy could potentially be explained by a ?healthy cohort? effect.
? Individuals who insist that all interventions need to be validated by a randomised controlled trial need to come down to earth with a bump.
Of course their conclusion takes the cake. ?..we feel assured that those who advocate evidence based medicine and criticise use of interventions that lack an evidence base will not hesitate to demonstrate their commitment by volunteering for a double blind, randomised, placebo controlled, crossover trial.?
I love it and certainly couldn?t have said it better.
Excellent.
Truth, Lies and Statistics?
Another even harder hitting article, if it can be believed, titled Why Most Published Research Findings Are False was published in The Public Library of Science journal Volume 2, August 2005 and reviewed in New Scientist August 2005.
The author John P. A. Ioannidis of the University of Ioannina School of Medicine, Ioannina, Greece, clearly states; ?Simulations show that for most study designs and settings, it is more likely for a research claim to be false than true.? He goes on to analyse this and other statements and reviews the nature of statistical analysis, relationships and bias.
I guess I could say ?It's all Greek to me??
Check it out as it certainly sheds some light on this age old debate.
KC & Mg2+
Staying with the Greek theme, way back in the late ?80s I noted a research paper by Anfitritis Thalasselis et al, titled Keratoconus, magnesium deficiency, type A behavior and allergy as published in what was then affectionately referred to as the ?yellow peril?. [Am. J. Optom. Physiol. Opt. 65, 499505. (1988)]
It piqued my interest as I'd been noting an apparent ?cluster? of keratoconics from the Pelindaba and Rustenburg areas, an hour or two from Pretoria where I practised.
What was interesting to me, in an anecdotal and observational way, was that many of the keratoconics lived and worked in Uranium mining and enrichment located around these parts, primarily for the atomic ?industry?. The area is well known for dolomitic rock, which is apparently also found in areas with rich Uranium content, limestone formations and so on. This area was also mined in the days of Paul Kruger, for the extraction of lime. I've spent great times in an amazing house in Broederstroom, near Pelindaba, created from the 19th century lime smelters they used and have seen some unusual luminous insects. One wonders if there were any radioactive leaks from the neighbours, but that's another story?
If you have Google Earth follow this link to view Pelindaba from the air. Zoom out and scroll to the left and you will see the Crocodile River and the area of the lime smelter and to the right my old home town, Pretoria. The American Military imaging for this site is particularly good, as are New Zealand?s Devonport naval base and the Waihopai spy domes. Most of the rest of the images of NZ and South Africa are just a big blur. Funny that!
Some of our earliest ancestors come from this area and lived in the massive limestone caves like Mrs Ples? Sterkfontein home. These caves develop from the interaction of water within limestone and dolomitic geological structures prevalent in the Pretoria-Witwatersrand area. Check out this outstanding and in depth paper on the Witwatersrand Supergroup - from which around 40% of all gold in the history of mankind has been mined. It details historical and geological aspects with some helpful diagrams. This whole area has amazing history and I am a proud owner of a very old stone age hand-axe I dug up in my garden.
I digress.
What?s interesting from a medical point of view is that dolomitic rock is also a source of magnesium [calcium magnesium carbonate], as many gardeners and takers of magnesium supplements and antacids will know. Additionally a respected physician, with whom I shared a number of keratoconic [and regular] patients, felt that magnesium deficiency was linked to hypertension and other atherosclerotic and circulatory disorders. He also reportedly felt that drinking water quality in that region was part of the equation.
As I say I found the article very interesting and have kept an eye out and an ear open for more on this subject. Indeed over the past years papers that mention or discuss the role of magnesium in corneal metabolism have certainly garnered my interest.
Thus Thalasselis? latest offering: The possible relationship between keratoconus and magnesium deficiency immediately attracted my attention.
In this review article the author succinctly covers the literature and discusses the histological features in KC and how magnesium deficiency can affect osmosis, corneal deturgescence, DNA-RNA synthesis, apoptosis-mitosis balance and cellular respiration. It also covers the role of Mg in enzyme and coenzyme function in the collagenous stromal tissue, fibroblastic action, clinical and lab studies and a whole lot more.
In summary Thalasselis states that magnesium deficiency may be a cofactor which may affect membrane integrity and function and increase the susceptibility of corneal tissue to oxidative stress. We have also heard other authors suggest using UV blocking contact lenses in KC. This may also help reduce another avenue of oxidative stress? I certainly include UV block in KC [and most other CL designs], where possible, and have done for years.
At this point we still don't know a lot about the aetiology and pathogenesis of KC and it is regarded as a condition of ?unknown cause?.
So does the cluster of KC cases I mentioned fall into a category where environmental factors have lead to magnesium deficiency? Or one could surmise that these people may represent the other extreme of potentially excess magnesium or the altered metabolism thereof? On the other hand it may be that living in these hot dusty conditions may lead to excessive eye rubbing, another co factor associated with KC. Is allergy a factor? It may well be that these cases were coincidentally simply genetic in origin in this mostly Afrikaans group with largely Dutch, German and French ancestry?
The point I am making is that assumptions based solely on anecdotes or observational data can also be way off the mark. At the same time if we notice ?trends? then this is a good basis for more scientific study, although the restrictions and limitations of such double blind, randomised, placebo controlled, crossover trials could also prove nothing either way?
I have previously proposed the ?Saks classification of Keratoconus? where I suggest, in an anecdotal and observational manner, that many cases of KC seem to occur in extremes of body somatype:- We have the rounder, jowlish, larger person [endomorph] where we often see large, sagging, geographic cones [as in many of the Polynesian type cones] and on the other extreme the steep, central nipple-cones typical of the smaller stature [ectomorphs] as we see in many Indian/Asian/Pakistani cones.
that's the point in discussing ?extremes? in this month?s missive.
Too much or too little magnesium? Endomorphs & ectomorphs. Evidence based versus observational medicine?
Extremes of action and function.
I have a desire for balance in matters optometric; and the universe in general.
Last Word.
I can?t say I got my birthday election wish; however the centre-shifted Labour should be a little more restrained and not so easily allowed to run amok with rampant legislative changes. Not that there are many traditional values left to mess with.
Helengrad is apparently having another name change. This time I hear it will forthwith be known as Saint Petersburg.
The King is dead. Long live Alonso.
Spaniard Fernando pulled it off in a French Car and is indeed the youngest F1 World Champ ever.
The promising summer start degenerated into the predicted wet and windy weather. We didn't mind too much as we had the ?dump of the season? in Queenstown just as the Southern Ski Fields were about to melt and close.
My early veggie patch survived the winds and is in fact thriving as the roots have had more than enough water. As I write this we've had our first five ripe tomatoes - two months ahead of schedule.
It's amazing how good a home grown tomato tastes after months of those tasteless, supermarket red-things filled with water.
Call them tomatoes?
For more information or any comments email Alan at incontact@optom.co.nz.