New book in Dutch

Eet vet word slank

Eet vet word slank gepubliceerd januari 2013

In dit boek lees je o.a.: * heel veel informatie ter bevordering van je gezondheid; * hoe je door de juiste vetten te eten en te drinken kan afvallen; * hoe de overheid en de voedingsindustrie ons, uit financieel belang, verkeerd voorlichten; * dat je van bewerkte vetten ziek kan worden.

Trick and Treat:
How 'healthy eating' is making us ill
Trick and Treat cover

"A great book that shatters so many of the nutritional fantasies and fads of the last twenty years. Read it and prolong your life."
Clarissa Dickson Wright

Natural Health & Weight Loss cover

"NH&WL may be the best non-technical book on diet ever written"
Joel Kauffman, PhD, Professor Emeritus, University of the Sciences, Philadelphia, PA

How Statistics in Medicine Can Be Misleading

When newspapers and scientists want to create the maximum impact for their (usually modest) findings in the field of prevention of heart disease or cancer, they publish the "relative risk" statistics, rather than "absolute risk" statistics.

To explain the two terms and their significance, let me give an example: If the chance of a thing happening is reduced from two per thousand to one per thousand, that is a "relative risk" reduction of 50%, which sounds a lot. But in reality, the "absolute risk" has gone down from 0.2% to 0.1%, or to put that another way, your chance of surviving has been increased from 99.98% to 99.99% which is really very small and nothing like as headline grabbing.

The following letter from Dr Uffe Ravnskov to the British Medical Journal concerns the misleading reporting of heart disease risk statistics on which decisions about aggressive intervention with statins are based.

Researchers claim clinical trials are reported with misleading statistics

BMJ, 18 June 2002

Prevention is better than cure, but the effect of most preventive measures is trivial.  The relative risk reduction is therefore highly misleading, as pointed out by Nuovo et al. (1), but even the absolute risk reduction, or number needed to treat, means almost nothing to most patients. For this group it is much more 'honest' and effective to provide the figures that represent their chances of surviving with and without treatment.
To give an impression of the small improvement that is achieved by commonly used preventive measures I have calculated the chance of surviving with and without treatment of hypertension, and with and without treatment of hypercholesterolaemia (table).   For hypertension I have used the figures from a meta-analysis of seventeen controlled, randomised trials (2). For hypercholesterolaemia I have used the data from the 4S (3) , as it demonstrated the most favourable outcomes in patients with established cardiovascular disease, and the data from the WOSCOPS trial (4) as this trial demonstrated the most favourable outcome in healthy individuals with high cholesterol. In both trials I have chosen the figures for total mortality, because I assume that this is the most relevant figure for most patients, and because no bias is associated with that outcome. For the hypertension trials total cardiovascular mortality is the measurement used, because a meta-analytic calculation of total mortality was not performed.  

Table. Benefits from treatment of high blood pressure and of high cholesterol BP
Relative risk reduction; %  -20 -29 -21
Absolute risk reduction; % -0.8 -3.3 -0.9
Chance of surviving without treatment; % 96 88.5 90.6
Chance of surviving with treatment; % 96.8 91.8 91.4

As mentioned, these figures are the most optimistic available. For instance, in many of the studies that were included in the meta-analysis on hypertension, total mortality was not reduced significantly. Further, the results from the most recent secondary preventive statin trial HPS were only half as good as those from 4S (5); and total mortality in the first primary preventive statin trial EXCEL was increased in the treatment group (6). If patients were given these odds, and then clearly informed about possible side effects from treatment, I guess that most of them might choose to spend their money on horse racing.

  1. Nuovo J, Melnikow J, Chang D. Reporting Number Needed to Treat and Absolute Risk Reduction in Randomized Controlled Trials. JAMA 2002;287:2813-4
  2. Hebert PR, Moser, M, Mayer J, Hennekens CH. Recent evidence on drug therapy of mild to moderate hypertension an decreased risk of coronary heart disease. Arch Int Med 1993;153:578-81.
  3. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S) Lancet 1994;344:1383-9.
  4. Shepherd J, Cobbe SM, Ford I, Isles CG, Lorimer AR, Macfarlane PW, McKillop JH, Packard CJ, for the West of Scotland Coronary Prevention Study Group. Prevention of coronary heart disease with pravastatine in men with hypercholesterolemia. N Engl J Med 1987;333:1301-7.
  5. Ravnskov U. Statins as the new Aspirin. Conclusions from the heart protection study were premature. BMJ 2002;324:789.
  6. Bradford RH, Shear CL, Chremos AN, Dujovne C, Downton M, Franklin FA, Gould AL, Hesney M, Higgins J, Hurley DP, et al. Expanded Clinical Evaluation of Lovastatin (EXCEL) study results. I. Efficacy in modifying plasma lipoproteins and adverse event profile in 8245 patients with moderate hypercholesterolemia. Arch Intern Med 1991;151:43-9.

Last updated 26 January 2003

Related Articles