Dr Dingle's Blog / medicine

Is your medicine killing you. Understanding the facts may save your life. The NNT

Is your medicine killing you. Understanding the facts may save your life. The NNT

Medical statistics are often used to justify the overuse of pharmaceuticals because they use different types and they are hard to understand then there is even a simpler number which is used in medicine, the Number Needed to Treat (NNT). This is how many people you need to treat to stop one negative outcome occurring. The negative outcome might be heart attack, stroke, cancer or even recurring ear infection. The NNT offers a measurement of the impact of a medicine or therapy by estimating the number of patients that need to be treated in order to have an impact on one person. In this case the higher the number the worse it is and the lower the number the more effective the medication. So an NNT of 1 is fantastic and an NNT of 100 is absolutely useless.

If a new drug reduced the death from heart attacks by say 50% (absolute statistics) then the number needed to treat is around 2 (NNT =2). So you only need to treat two people to have a benefit and save one life. This is great. If the new drug cuts the heart attack rate by only 25%, that is 1 in 4 then the NNT is 4. If the drug is only one percent effective which means of the 100 people given the drug it will only potentially (remember we are not even considering the side effects here) save one life, like the statin drugs, then the NNT is 100.

Fortunately the NNT is well established in medicine but not widely promoted. One website however TheNNT.com puts all this information in one place. Even for the most skeptical GP’s and specialists and it is available free to everyone. Just as important it is a group of physicians, medical doctors, that have collected the information. They only use the highest quality, evidence-based studies (frequently, but not always Cochrane Reviews), and they accept no outside funding or advertisements so they are independent of pharmaceutical companies.

In addition, for every therapy they review, they provide a color-coded summary for you to use (borrowed from the traditional stoplight). Unlike most sites this group also report harm that may be caused by the drug or the procedure and then they rate them into a stoplight colour coded. They have developed a framework and rating system to evaluate therapies based on their patient-important benefits and harms. The therapies rated green are the best you can get – there is clear evidence of benefits which clearly outweigh any associated harms. For example: Steroids for Asthma Attack: if you give steroids to 8 patients with asthma attack in the emergency department, you prevent one from having to be admitted to the hospital. There are definitely side effects to steroids – high blood sugar, hyperactivity – but are considered minor in comparison. The NNT for this treatment is 8. Remember the lower the number the better. Therapies rated yellow require more study because they don't think the data is conclusive or substantial enough to be able to give a clear rating yet. So they are not recommended but if you do use them go with caution. Red suggests that while there may be some benefits, they are far outweighed by the harms. One extreme example: if a medicine were to save 2% of people's lives, but cause strokes in 10% of people, it's hard to say that this medicine clearly is overall helpful. Black is the "worst" or "lowest" rating. Therapies rated black have very clear associated harms to patients without any recognizable benefit. What is frightening is that most of the major medications and procedure used for cardio vascular disease fit into the black.

While there are many drugs and procedures listed I will start with some of the common procedure for cardio vascular disease as this is the biggest killer and there is just not enough space here to cover all the listings on TheNNT.com web site. For statin drugs for acute coronary syndrome the NNT is  0% in other words no person who took the drug were helped (life saved; heart attack, stroke, or heart failure prevented) however,  an unknown number were harmed (medication side effects/adverse reactions). This was put on the black list. Statins Given for 5 Years for Heart Disease Prevention (With Known Heart Disease) NNT was 83. In fact they reported 96% saw no benefit however 1% were harmed by developing diabetes and 10% were harmed by muscle damage, just two of the side effects. This is also put on the black list as the harm outweighs any insignificant benefit of the drugs. Statin Drugs Given for 5 Years for Heart Disease Prevention (Without Known Heart Disease) also put on the black list and has a NNT of 104 for non-fatal heart attack but they reported 0% life saved and 1 in 100 were harmed, they develop diabetes and 1 in 10 had severe muscle damage. In contrast, they reported the Mediterranean Diet for Secondary Prevention After Heart Attack got the green light and a NNT of 30 for mortality and no negative side effects and as low as 1 in 18 were helped. Not to mention the other benefits in other conditions such as cancer and diabetes.

Beta Blockers for Acute Heart Attack (Myocardial Infarction) are also commonly prescribed by specialists are put on the black list and listed with no benefit, but 1 in 91 were harmed by cardiogenic shock. Hormone Replacement Therapy for Cardiovascular Prevention of a First Heart Attack or Stroke, black list and no benefit found but 1 in 250 were harmed (heart attack due to HRT oops, exactly what they were supposed to prevent), 1 in 200 were harmed (stroke due to HRT)  and 1 in 100 were harmed (blood clot in the leg/lung). To support this a recent study which investigated 27 trials found only one trial showing a 0.7% benefit and 26 trials that suggest no aggregate mortality benefit to beta-blockers. All the more recent, and larger, trial that utilized double-blind techniques (COMMIT, 2004) found no benefit.

Even putting a stent (a little piece of artificial artery) in an artery got on the black list. In the case of Coronary Stenting for Non-Acute Coronary Disease Compared to Medical Therapy none were helped, that is no life saved, no heart attack prevented, and no symptoms reduced, however, 1 in 50 were harmed including complications such as bleeding, stroke, kidney damage. Coronary Artery Bypass Graft Surgery (Heart Bypass) for Preventing Death over Ten Years was marginally better. The NNT was 25 to prevent death however, 1 in 83 died, 1 in 100 had stroke, 1 in 43 had kidney failure, 1 in 28 in the operation, 1 in 14 required extended life support and get this, 1 in 3-5  had cognitive decline. Not such a good outcome if you look at the whole picture and any wonder it was put on the black list

 Aspirin Given Immediately for a Major Heart Attack (STEMI). Got the green light. So if you have a heart attack taking an aspirin straight away has some benefit. The NNT was 42 for mortality as 1 in 42 were helped (life saved) but 1 in 167 were harmed (non-dangerous bleeding). However, with Aspirin to Prevent a First Heart Attack or Stroke the NNT was 1667 for cardiac benefit, that is 1 in 1667 were helped (cardiovascular problem prevented), 1 in 2000 were helped (prevented non-fatal heart attack) and 1 in 3000 were helped (prevented non-fatal stroke). But no deaths prevented and 1 in 3333 had a major bleeding event.

The NNT for Blood Pressure Medicines for Five Years to Prevent Death, Heart Attacks, and Strokes were 125, 1 in 67 prevented stroke, and 1 in 100 prevented heart attack. However, 1 in 10 had side effects and stopped taking the drug. Treatment of Mild Hypertension for the Primary Prevention of Cardiovascular Events was given the yellow light and the there was no NNT as no benefit was found. However, 1 in 12 experienced medication side effects.

On a positive note oral anticoagulants (warfarin) for primary stroke prevention (no prior stroke) got the green light and the NNT was 25 for prevented stroke and 1 in 42 were helped (preventing death from any cause). However, 1 in 25 were harmed (having bleeding), 1 in 384 were harmed (intracranial hemorrhage).

It seems we spend billions of dollars, even trillions of dollars on drugs and procedures that don’t work and and are likely to be doing more harm than anything just because of trust and a lack of knowledge on statistics. While I am likely to criticized for presenting this information and you might question your doctor or specialist, remember I am just the messenger presenting factual numbers. See for yourself www.TheNNT.com.

Read more →




“Walking is man's best medicine.”- Hippocrates

Walking is probably the most underestimated and undervalued activity we do. We often take it for granted until we have some injury or can no longer walk, while it is probably the single most important activity that keeps us healthy, alive and adds to the quality of our lives. As well as the benefits to health walking has potentially important environmental and social implications. It is also the least likely activity that is going to cause injury as we are designed to walk. Fossil records show that we have been walking (bi-pedal) for around 4 million years. That is a lot of walking and as time has progressed we have become better at it.

Walking is the most common and preferred activity for people, for example in the US 54% of women and 41% of men cite walking as their most common activity during the past month 1 and it as the most frequently reported physical activity among high school students 2. While it might be the major activity we just don’t do enough of it. In England, for example, 29% of adults do less than 30 min of moderate physical activity per week and about 8% do not even walk continuously for 5 min over 4 weeks 3

Just as important however is the speed of walking. Walking at a pace of 5–8 km/h expends sufficient energy to be classified as moderate intensity and is an easy and accessible way of meeting physical activity recommendations. Studies have also shown the speed of walking is important - in a meta-analysis of five studies (14,692 participants total), people in the slowest quarter of walking speed, had significantly higher mortality rates than did those in the fastest quarter 4, that is the faster walkers live longer. A very good reason to up the pace a bit. An average walk (not a stroll) is about 5.0 kilometres per hour (km/h) up to 6.5 or 7 km/h for a brisk walk.

Walking offers many benefits to health, whether it be preventing disease, contributing to emotional and cognitive health, or helping to maintain independence later in life. Walking is the real “wonder drug” that we all need to be taking. And while the benefits are multiple and the behavior is simple most of us don’t do enough of it. In effect the benefits of walking can been seen to outstrip all the potential for pharmaceutical drugs on the market place and in many cases walking can be seen as an alternative to conventional drug therapy. The health benefits and resulting medical care savings of walking and physical activity are extremely large. Further, these benefits accrue regardless of age, weight, or existing health challenges. In a study of institutionalized elderly women aged over 70 walking 50-65% of the maximum heartbeat had the effect of decreasing blood pressure together with improvement in flexibility, left hand grip strength, sense of equilibrium, self-esteem, depression and life satisfaction 5. People only need to be active for at least 150 minutes a week and it can occur in short bouts, lasting at least 10 minutes or longer periods if you like. But the more you walk, the faster and the bigger the steps you take the longer you live. No other activity shows up with so many benefits as walking.

Systematic reviews and meta-analyses have shown walking to have various and multiple health benefits including positive effects on fitness, fatness, blood pressure control, weight loss, depression and other areas of mental health and stress, and cardiovascular disease risk prevention, pain management and spinal support as well as some cancers such as colorectal cancer. A systematic review of walking found statistically significant reductions in body fat, BMI and blood pressure and increases in breathing capacity 6. The review reported a reduction in blood pressure of around 3.72 mm Hg, around the same lowering from most of the pharmaceutical drugs on the market. The greatest benefit was reported in those involved in group walking 6. This reduction is comparable to earlier large studies of walking and resting blood pressure 7 which found a 2% reduction in blood pressure from walking. The importance of this difference becomes significant when you know that a 2 mm Hg reduction in blood pressure can reduce coronary heart disease risk by 6% and stroke and trans-ischaemic attacks (transient strokes) by 15%. 8. While other studies have reported a reduction of only 2 mm Hg in blood pressure could reduce stroke mortality by 10% and mortality from vascular causes in a middle-aged population by 7%.

Walking has also been associated with a reduced risk and even playing a role in reversing type 2 diabetes. A Harvard University study examining the exercise habits of more than 70,000 women, showed that a 40 minute walk every day reduced type 2 diabetes risk by 40%, and with a longer walk the risk could be decreased by an even larger percentage. Even adults with Diabetes, those who walked for 2 or more hours a week lowered their mortality rate from all causes by 39 per cent. However, the timing of walking also appears to be important. Walking after a meal reduces the blood sugar and lipid levels by increasing their absorption into the muscles. Walking after a meal the sugar and lipids are directed into the muscles not to be added as fat around the liver. When you walk you use more than 200 different muscles which create healthy molecular signals which positively alter the body’s biochemistry and metabolism. One of these is a particular muscle chemical, lipoprotein lipase (LPL), a protein enzyme has been studied in depth because this enzyme has a central role in several aspects of lipid (fat) metabolism. LPL controls plasma triglyceride (fat) breakdown (burning the fat into energy), shifting the cholesterol from LDL to HDL and other metabolic risk factors decrease when we stand or begin walking. The importance of producing enough LPL cannot be underestimated as people who produce less LPL have a five-fold increase in the risk for death and greater chronic heart disease. The production of LPL is therefore extremely beneficial to us.

Regular walking is beneficial for enhancing mental health, for example, reducing physical symptoms and anxiety associated with even major stress. In a study of Post Traumatic Stress (PTSD) symptoms, depression, anxiety and stress, sleep quality,  in 76 participants age, 47 they found total PTSD symptoms, combined symptoms of depression, anxiety, and stress, and sleep behavior were significantly and negatively associated with total walking time and that increased PTSD symptoms were associated with lower levels of walking. 10. In a study of twenty healthy, elderly adults with a mean age 70, negative feeling scores such as tension-anxiety, anger-hostility, and confusion significantly improved after walking 11.

Depression is a common disorder worldwide widely recognized now to be an inflammatory condition and not one of a serotonin imbalance like the drug companies want you to think. Walking has been shown to alleviate depression. In a Meta-analyses using eight trials showed that walking has a statistically significant, large effect on symptoms of depression 12 and no negative side effects. In a study investigating the mood in 102 sedentary, ethnic minority women over a five-month period they found walking significant decreased depressive mood and an increase in walking over the course of the study was associated with change in vigor 13. One study of fifty breast cancer patients reported 12 weeks of moderate intensity walking mid-way through chemotherapy had positive effects on fatigue, self-esteem and mood. The study reported 80 % adherence rate to completing the 12-week intervention and recording weekly logs and reported the self-managed, home-based intervention was beneficial for improving psychosocial well-being 14

Walking has also been found to improve our brain development. Older adults, who walk frequently, have lower risk for cognitive decline in later life. In a study of 299 adults, aged 65 or older, greater levels of walking, predicted greater volumes of frontal, occipital, entorhinal, and hippocampal regions of the brain, 9 years later. Walking 72 blocks, was necessary to detect increased grey matter volume, but walking more than 72 blocks added additional brain volume. Additionally, greater grey matter volume with walking reduced the risk for cognitive impairment 2-fold. Greater amounts of walking were associated with greater grey matter volume, which is in turn associated with a reduced risk of cognitive impairment. These findings are in line with data that, aerobic activity induces a host of cellular cascades that could conceivably increase grey matter volume 15.

We now know that Alzheimer’s disease is a cardiovascular condition related to blood flow and nutrients reaching the brain. Epidemiological data support an inverse relationship between the amount of physical activity including walking undertaken and the risk of developing both Alzheimer’s and Parkinson’s disease 16,17. Beyond this preventive role, exercise may also slow down their progression 18,19. Several mechanisms have been suggested for explaining the benefits of physical activity and walking in the prevention of Alzheimer’s. Walking improves the efficiency of the capillary system and increases the oxygen supply to the brain, thus enhancing metabolic activity and oxygen intake in neurons, and increases neurotrophin levels and resistance to stress. Walking activates the release of neurotrophic (brain growth) factors and promotes the formation of new blood vessels, facilitating the generation of new neurons and synapses, which in turn improve memory and cognitive functions 20.

Research with Alzheimer's Disease subjects has shown that walking plus conversation has an even better preventive effect than walking alone 21, suggesting that the "socialization effect" of exercise is an important aspect. In another controlled exercise trial, the practice of walking combined with bright light exposure improved sleep among Alzheimer's Disease patients 22 suggesting that we should be doing more of our walking outside in the sun with our friends.

Other co-benefits of regular walking include improved academic and job performance and improved community cohesion. Creativity has a number of positive benefits. Studies have found gains in participants’ ideational fluency (creativity) after aerobic running or dancing 23, with similar results for aerobic walking, regardless of participants’ fitness history 24,25. Whether one is outdoors, or on a treadmill, walking improves the generation of novel yet appropriate ideas, and the effect even extends to when people sit down to do their creative work shortly after. A group of four separate experiments by the same research group showed walking boosts creative ideation in both real time, and shortly after each of the four experiment variations. In the first experiment it was shown that walking increased the creativity of 81% of participants. In the second experiment, an increase in creativity, was still seen when participants were seated after walking. Experiment 3, demonstrated that walking outside prompted the most novel and highly creative thinking, when compared to those sitting inside and out, and walking inside. Walking is believed to promote free flow of ideas, being a simple and robust solution to increasing both creativity and physical activity 25. Perhaps every workforce should add some walking time?

 “All truly great thoughts are conceived by walking.”- Friedrich Nietzsche (1889)

  1. Watson et al
  2. Song et al
  3. Farrell L, et al. 2013
  4. Murtagh et al., 2015
  5. Son and Lee. 2001
  6. Murphy et al 2007
  7. Kelley et al. 2001
  8. Cook et al. 1995
  9. Lewington et al 2002
  10. Rosenbaum et al 2016
  11. Erickson et al 2011
  12. Robertson R, et al. 2012
  13. Lee et al 1999
  14. Gokal et al 2015
  15. Erickson et al., 2010
  16. Alonso-Frech et al 2011;
  17. Norton S et al 2014
  18. Ahlskog 2011;
  19. Pitkälä et al. 2013
  20. Paillard et al 2015
  21. Tappen et al 2000
  22. McCurry et al 2011
  23. Gondola, 1986, 1987
  24. Netz, et al., 2007
  25. Oppezzo and Schwartz, 2014





Read more →