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Sunday September 1, 2013 MYT 12:00:00 AM
Sunday September 1, 2013 MYT 8:18:23 AM
by tan shiow chin
Smokers may know that their habit causes lung cancer, but that doesn’t stop the majority of them from puffing away. – Bernama
We may believe that all our medical decisions are governed by logic and reason, but people often act according to their own opinions, whether founded or unfounded.
ONE of the cornerstones of modern medicine is evidence-based practice.
According to one of the pioneers of this concept, Canadian clinical epidemiologist Prof Emeritus Dr David Sackett, this is defined as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research.”
The practice of modern medicine subscribes to the basic tenet of science itself, namely, that any hypothesis or scientific question needs to be tested objectively and proven one way or the other in a consistent and repeatable manner.
For example, a common hypothesis in medicine would be: “Is drug A better than drug B for disease C?”
In order to test this hypothesis, a series of clinical trials would be initiated.
Ideally, these should be double-blind randomised clinical trials with hundreds or thousands of patients involved.
The double-blind and randomised aspects are to ensure that there is no bias in the implementation or interpretation of the study, as it means that neither the researchers nor the patients know who is receiving drug A and who is receiving drug B.
And typical sample population sizes of hundreds or thousands is to ensure that the result of the clinical trial is not a false negative, that is, showing that drug A is not better than drug B when it actually is. (Note: There is a formula to calculate the exact number of patients needed for any particular trial of this sort, based on a commonly-accepted level of statistical power required for drug trials.)
The results of the trials would need to show that drug A has a significantly better therapeutic effect on disease C, compared to drug B.
And most importantly, this result should be reproducible when other researchers conduct the same study on other similar patients.
This objective and logical approach towards proving whether a drug works or not is what convinces most of us who have grown up in the science-dominated modern age, of the effectiveness of modern medicine.
However, not everyone subscribes to evidence-based practice.
Vaccination as a cause of autism
A classic example of this would be the belief, held by certain groups, that the MMR (measles, mumps and rubella) vaccine causes autism.
Championed by actress and talk show host Jenny McCarthy, the basis for this belief started from a study published by medical journal The Lancet in February 1998.
This study, led by now-deregistered British gastroenterologist Andrew Wakefield, linked findings of bowel disease and developmental regression – mostly identified as autism – in the 12 children studied to “possible environmental triggers”.
The paper related how eight out of the 12 sets of parents whose children were in the study associated the development of their previously-normal child’s condition to the administration of the MMR vaccine.
While the authors of the study did not explicitly link the vaccine to the children’s developmental and gastrointestinal problems, the subsequent press conference publicising the study saw Wakefield stating that he could no longer morally support the administration of the triple vaccine until further research had been done to determine if the vaccine did indeed give rise to developmental and gastrointestinal complications in those who receive it.
Fifteen years later and no scientist has managed to find any link between autism and the MMR vaccine, despite a fair number of large scientific studies looking into the question.
Meanwhile, The Lancet retracted the entire paper in February 2010, while 10 out of Wakefield’s one dozen co-authors had earlier retracted their interpretation of the study in March 2004.
However, the damage had already been done.
According to UK government agency Public Health England, in 1998, the number of laboratory-confirmed cases of measles, mumps and rubella in the country were 56, 121 and 119 respectively.
Provisional data last year showed that this had increased to 2,030 and 2,466 for measles and mumps respectively, although decreased to 65 cases for rubella.
In particular, the current measles epidemic in the UK has been directly attributed to the scare caused by Wakefield’s claims 15 years ago, as most current patients are unvaccinated older children and teenagers.
MMR vaccination rates in the UK plummeted from over 90% to 54% between 1998 and 2004, although it has now increased back up to 91% in 2011-12.
But even today, after the scientific evidence has been disproved, there are many parents who still refuse to let their children receive the MMR vaccine for fear that it will cause autism, despite the protection it gives against the three infectious, and potentially lethal, childhood diseases.
Just can’t quit
Another example of people failing to make appropriate decisions based on obvious evidence is when it comes to the habit of smoking.
According to the World Health Organisation, the use of tobacco directly kills more than five million people every year, while over 600,000 more die as a result of exposure to secondhand smoke.
There are at least 250 known harmful chemicals in tobacco smoke, more than 50 of which are known to cause cancer.
And yet there are over one billion smokers worldwide.
In Malaysia, the 2012 International Tobacco Control Malaysia National Report stated that 84% of the 1,867 adult smokers and 90% of the 112 youth smokers surveyed had a “bad” or “very bad” opinion of smoking.
In addition, 88% of adult smokers “agreed” or “strongly agreed” that they would not have started smoking if they could go back and do it over again, while over one-quarter (27%) of youth smokers regretted starting the habit “a lot”.
However, only 42% of adult smokers “often” or “very often” seriously thought about quitting the habit, although two-thirds of them had tried quitting at some point previously.
This number was even less for youth smokers, with only 17% wanting to quit “a lot”, and 31% having attempted to quit within the past month.
And this is not due to ignorance of the health consequences of smoking either.
At least two-thirds of the smokers are aware of some of the harmful effects smoking has on the body. (See It’s bad for me)
Over 90% are aware that smoking causes chronic obstructive pulmonary disease (COPD) and heart failure, while around 80% know that it causes stroke and mouth cancer.
Between 68% and 76% are also aware that smoking can cause miscarriages, gangrene, premature ageing and male impotence.
In fact, personal health was only the second most influential reason for smokers to consider quitting their habit; the first was disapproval of the habit by family members.
Now, it is widely accepted by the public and the scientific community that AIDS (Acquired Immune Deficiency Syndrome) is caused by the human immunodeficiency virus (HIV).
However, there are groups of people who believe that this is not the case, one of the most influential being University of California, Berkeley, professor of molecular and cell biology Dr Peter Duesberg.
Prof Duesberg, who is otherwise respected for his cancer research, is a strong proponent of the belief that AIDS is actually caused by long-term usage of recreational drugs and/or anti-retroviral medications, rather than HIV.
His views, although conclusively disproved by several large studies, have influenced many people, most notably the South African government of then-President Thabo Mbeki (1999-2008).
Instead of HIV infection, Mbeki blamed the AIDS epidemic in his country on poverty, malnutrition and general ill-health.
In fact, his Health Minister Dr Manto Tshabalala-Msimang – an obstetrician and gynaecologist by training – promoted the benefits of beetroot, garlic, lemons, beer and African potatoes, as well as good general nutrition for the treatment of AIDS.
At the same time, she decried the toxicity of anti-retroviral drugs that were proven to control HIV infection, and discouraged her fellow countrymen from consuming those life-saving medications.
A 2008 Harvard School of Public Health study published in the Journal of Acquired Immune Deficiency Syndrome estimated that around 365,000 South African deaths could have been prevented if the Mbeki government had not delayed the rolling-out of a national anti-retroviral treatment programme due to these beliefs.
Although such a programme was started in 2003 under Mbeki’s administration, its reach was limited, and far behind other African nations with similar HIV/AIDS problems, like Botswana and Namibia.
The national treatment programme only really took off once Mbeki was succeeded by Jacob Zuma in 2008.
Zuma replaced Dr Tshabalala-Msimang with Barbara Hogan, who publicly declared that the age of AIDS denialism was over in South Africa.
Tags / Keywords:
Health, evidence-based medicine, smoking, vaccination, HIV, AIDS
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