Why do we need evidence-based medicine, BMJ Best Practice

Why do we need evidence-based medicine?

In the past, doctors didn’t always have access to the latest medical research. They often decided how to treat patients using only their own judgement and experience and what they learned at medical school. We now know that this is not the best way to practise medicine. This is because what doctors think is best for a patient is not always what the research shows is best.

When researchers study a disease or a condition, they usually look at many more patients than any one doctor will ever treat. Also, medical knowledge changes all the time. And what doctors used to think was the best thing to do, even a few years ago, might actually be considered harmful today.

Only by looking at all the evidence and judging it fairly can you work out what the research really says about a treatment. This is called practising evidence-based medicine.[1]

Key points about evidence-based medicine

  • All evidence is not alike. Some evidence is better than other evidence.
  • When doctors look at the research before recommending a treatment, they are using evidence-based medicine.
  • Evidence-based medicine looks at all the research that there is about a disease or treatment.
  • When researchers look at whether a treatment works, they look at many more patients than a single doctor will ever treat.
  • Sometimes the evidence can’t tell you which treatment is best for you, so it’s important that you weigh up the benefits and harms of treatments carefully.

Why evidence from research is so important

All evidence is not alike. It can be dangerous to rely on what your neighbours or friends tell you. For example, just because a cancer drug worked for them, that doesn’t mean it will work for you. Also, there have been many practises in medicine that were later found to be useless or even harmful when studies were done.

Here are some examples:

  • Fifty years ago, women were often given an enema while they were in labour. This is uncomfortable and unpleasant. But doctors thought that enemas would reduce the risk of infection for the woman and her baby. Some hospitals gave soapy enemas, which were painful for women. When doctors studied the results from the research they found there was no evidence that enemas prevented infections. Two studies showed that enemas made more of a mess, and women felt embarrassed by the enema.[2] Women no longer have enemas while they’re in labour.
  • Resting in bed used to be recommended for many conditions. But now we know that it can often do more harm than good. People who have had a heart attack, for example, do better both physically and mentally if they begin exercising as soon as they feel well enough.[3]

Sometimes research has proved that a treatment works, but doctors have been slow to start using the treatment. For instance, tens of thousands of premature babies died because a treatment that could help them breathe better was not widely used. In 1972, the first of several studies was published showing that giving drugs (called corticosteroids) to women about to have a premature baby could help the baby’s breathing.[4] But it was another 20 years before obstetricians (doctors who specialise in pregnancy and childbirth) began using these drugs regularly.

How to weigh other sorts of evidence

What friends and family say
When you aren’t well, your family and friends often give you advice and tell you about their experiences. These stories can be very powerful. If your mother says that your son needs to have his tonsils taken out because he has had so many sore throats, you may believe what she says because she is your mum. She may say that, when you had your tonsils out, you stopped missing school and started eating better and growing more.

But research shows that removing children’s tonsils may not do them much good, and after a year or two they may have as many sore throats as children who didn’t have their tonsils out.[5] And some children get complications from tonsil surgery, such as bleeding. Your mum means well, but one person’s story is just that: it is the story of one person who had a treatment. It is not the story of thousands of others who also have had it.

For example, you often hear stories of people who have survived cancer because they went on strict diets. However, you are less likely to hear about people who went on strict diets and died. They are not around to tell their stories. It can be hard to follow a strict diet if you have cancer and find eating difficult. It may keep you from enjoying your life. You should think carefully before you start a diet that is difficult and unpleasant to follow, and do it only if research shows that you will get some real benefits from it.

However, you can still learn a lot from one person’s experience of treatment. Research studies do not always look at the things that matter to you. What friends and neighbours and other people with your condition say is important. But you shouldn’t use this information on its own when you make decisions about treatment.

What your doctor says
Ideally, your doctor’s treatment recommendations will be based on the most reliable research available. But it’s tough for busy health professionals to keep up to date with advances in medical knowledge. A 1992 study found that a doctor would have to read 17 articles in medical journals every day of the year to keep up with new information in their area of medicine.[6] This number could be even higher today.

However, more medical information is now summarised to make it easier for doctors to keep up to date. Even so, not all doctors use this type of information. Also, the research doesn’t always provide a clear answer on what treatment works best, so different doctors will come to different conclusions. For men with prostate cancer, for example, some doctors recommend surgery, others recommend radiotherapy, and others think some men will do just as well without any treatment.[7]

What the experts say
Your doctor may be an expert in their field. Or your doctor may decide how to treat you based on what other experts say. Much of what doctors learn at medical school is based on what experts think. Doctors like to ask their colleagues for advice.

But experts don’t always get it right. It is safer to rely on the results of good research studies than on one person’s opinion.

What the media say
Every day there are stories in newspapers or on television about the latest discoveries in health care. One day you may hear that drinking alcohol can lower your chance of heart disease. The next day you may hear that it can increase your risk of breast cancer. What should you do?

The media often report on the results of just one study. There may have been other studies that had different results, and the reporter may not know about these. Usually, any one study just adds a brick into a growing wall of evidence. The results of one study cannot tell you the whole story. It is only after other groups of researchers repeat the study and find the same results that answers become reliable.

You do not need to make a decision on the basis of one study.

The media also tend to be optimistic about advances in medicine. For example, a study that looked at how the media reported on drug treatments for osteoporosis and high cholesterol found that the benefits of the drugs were stressed but the possible harms were barely mentioned.

There are also a lot of websites that provide health information. But it can be hard to know which ones to trust.

What tradition says
Just because something has been used for years doesn’t mean it works or can’t hurt you. Many complementary and alternative medicines (such as herbal products and vitamins) have been used for years. But there isn’t always good evidence that they do more good than harm.

One study looked at seven reference books.[8] It found that more than 100 different complementary medicines were recommended for asthma. But there was no good evidence that they worked.

Traditional remedies may have been used for centuries, but they may not be safe when taken with modern medicines. St. John’s wort, for example, is a herbal remedy for depression. Unfortunately, it stops some drugs, such as the contraceptive pill and blood-thinning tablets, from working properly.

Questions to ask your doctor
Here are some questions that might help you weigh up the information you find in the media or on the Internet about treatments. You could show these questions to your doctor.

  • How could this treatment help me? Has it been studied in people like me?
  • Is it likely that this drug will harm me? Am I more likely to get side effects than other people? (For example, older people sometimes have more side effects.)
  • How strong is the evidence that this treatment works? Are the results of the research published in a medical journal? Is just one person telling their story on television?
  • What are the alternatives to the treatment being offered?
  • What are the costs of the treatment? (These can include financial and non-financial costs, such as inconvenience.)


11 Things to Know About Pot and Your Health

Do marijuana’s benefits outweigh its risks? Here’s a look at the pros and cons of the drug.

As more states legalize marijuana, it’s important to know the pros and cons of pot—and what exactly it might do for your health.

Health looked at recent research and spoke with several experts about who might want to try it, who should avoid it, and what any marijuana user should know.

It may help with anxiety and PTSD

The relaxing effects of marijuana are well known, so it’s not surprising that a 2016 paper in the journal Clinical Psychology Review concluded that it may have benefits for people with depression, social anxiety, and post-traumatic stress disorder. A study published in Drug and Alcohol Dependence also found that a very low dose of THC, one of the main compounds in marijuana, helped people feel less nervous about a public-speaking task.

But it may not be that simple: That dose was equivalent to only a few puffs on a marijuana cigarette, say the study authors. They also found that slightly higher amounts of TCH—anything that would produce even a mild high—actually made anxiety worse. Other research has also suggested that marijuana may be more harmful than helpful for people with certain mental health conditions, like psychosis or bipolar disorder.

The research “indicates cannabinoids could be helpful for people with anxiety,” lead author Emma Childs, PhD, associate professor of psychiatry at the University of Illinois at Chicago, tells Health. But more research is needed, she says, to determine appropriate dosages and delivery methods, and to prevent the opposite effects from happening.

It can relieve chronic pain and nausea

Pain relief is a common use for medical marijuana, and the National Academies of Sciences concluded there is indeed good evidence to support this practice. Marijuana products also appear to be effective at calming muscle spasms caused by multiple sclerosis and easing nausea and vomiting due to chemotherapy, the report stated.

The National Academies also determined that there is moderate evidence that cannabis or cannabis-derived products may help people who have trouble sleeping due to sleep apnea, fibromyalgia, or chronic pain.

People with epilepsy may benefit—even kids

In a New England Journal of Medicine study, cannabidiol oil—a derivative of marijuana—reduced seizures by 39% in children with Dravet syndrome, a rare form of epilepsy. That was big news for parents who have been using medical marijuana for years, often illegally, to help their kids suffering from this debilitating condition.

The cannabidiol oil used in the study—approved by the FDA in 2018 and marketed as Epidiolex—won’t make people high, because it doesn’t contain THC. Experts say that results may be riskier and more unpredictable with other marijuana products.

It may be a safer alternative to opioids

Despite beliefs that marijuana is a “gateway drug,” research suggests that the use of medical marijuana may actually reduce dependence on dangerous prescription painkillers like those fueling the nation’s opioid epidemic.

In a 2016 study in the journal Health Affairs, researchers found that there were 1,826 fewer daily doses of painkillers prescribed per year, on average, in states where medical marijuana was legal compared to states it’s not. And in a review article published in Trends in Neuroscience, researchers wrote that cannabinoids may help people recover from opioid addiction. Human trials have been limited because of marijuana’s classification as a Schedule 1 drug—but the authors argue that more studies are urgently needed.

It may have anti-cancer effects, but research is limited

Olivia Newton John uses cannabiodiol oil (along with conventional medicine) to fight her metastatic breast cancer, the actress’s daughter recently revealed. Studies have shown that the oil may inhibit the growth of cancer cells outside of the human body, but there haven’t been any real-life trials to back up these findings.

Gregory Gerdeman, PhD, assistant professor of biology at Eckerd College, told Time that there have also been anecdotal patient reports and “increasing numbers of legitimate clinical case studies … that all indicate tumor-fighting activities of cannabinoids.” It’s still unknown, however, whether traditional forms of marijuana would be an effective cancer therapy, or what cancer types it might actually work against.

Parents (and expectant parents) should know the risks

As pot use becomes more prevalent, more pregnant women are getting high, according to a 2016 JAMA study—either for recreational use or, sometimes, to treat morning sickness. But evidence suggests that prenatal exposure to marijuana is associated with developmental and health problems in children, including low birth weight, anemia, and impaired impulse control, memory, and attention, the authors wrote. Until more is known for sure, they say women who are pregnant or considering becoming pregnant should be “advised to avoid using marijuana or other cannabinoids.”

Current parents should also use marijuana with caution, University of Washington researchers suggest. Their study in Prevention Science found that people tend to cut back on marijuana use once they have kids, but they don’t always quit. That’s concerning, says lead author and research scientist Marina Epstien, PhD, because parental marijuana use is strongly related to children’s use—and children’s use is associated with higher rates of health problems.

“Children watch what their parents do,” Epstein tells Health. “I would encourage parents to be talking to their kids and be clear about expectations for their kids about using or not using marijuana and the amount, especially with their teenagers.”

Heart problems could make it extra risky

In 2014, a study in Forensic Science International documented what German researchers claimed to be the first known deaths directly attributed by intoxication from marijuana. The authors pointed out that, during autopsies, it was discovered that one of the two young men had a serious but undetected heart problem, and that the other had a history of drug and alcohol use.

The researchers concluded that the absolute risk of cannabis-related cardiovascular effects is low, especially for healthy people. But they say that people who are at high risk for heart-related complications should avoid the use of cannabis, since it can have temporary effects on the cardiovascular system.

It’s not safe to use marijuana and drive

A study by the Insurance Institute for Highway Safety found that insurance claim rates for motor vehicle accidents from 2012 to 2016 were about 3% higher in states with legalized marijuana than in states without. But other studies have found no such increase in fatal car crashes in states with legalized marijuana, compared to similar states without.

Experts say it’s possible that driving under the influence of marijuana may increase the risk of minor fender benders—but may also reduce rates of alcohol consumption and therefore help prevent more serious, deadly crashes. The bottom line? Driving while stoned may be less dangerous than driving drunk, but it’s still riskier than driving sober.

Weed smoke is still smoke—and still has health risks

The Canadian Research Initiative in Substance Misuse published a set of “lower-risk cannabis use guidelines,” aimed at helping people who use marijuana make responsible decisions about their health. (The drug was legalized for recreational use in Canada in 2018.) Among other advice, the guidelines urge people to “avoid smoking burnt cannabis,” which can harm the lungs and respiratory system—especially when combined with tobacco.

They recommend choosing vaporizers or edibles instead, but caution that these methods also come with some risks. And if you do smoke cannabis, the guidelines say, “avoid ‘deep inhalation’ or ‘breath-holding,’” which increase the amount of toxic materials absorbed by the body.

It’s not just lung-health that frequent weed smokers should worry about, either. A study in the Journal of Periodontology found that frequent marijuana users were twice as likely as people who didn’t use frequently to have gum disease, even after controlling for other factors such as cigarette smoke. The research didn’t distinguish between methods of marijuana use, but they do point out that smoking is the most common form of recreational use.

For recreational users, less is safer

Canada’s low-risk guidelines may sum it up best with this statement: “To avoid all risks, do not use cannabis. If you decide to use, you could experience immediate, as well as long-term risks to your health and well-being.” The guidelines also recommend avoiding marijuana use during adolescence, because the later in life people start using the drug, the less likely they are to experience these problems.

Finally, the guidelines recommend adults choose natural cannabis over dangerous synthetic versions, and limit themselves to “occasional use, such as on weekends or one day a week at most.”

Some marijuana users develop a condition called cannabinoid hyperemesis syndrome

Cannabinoid hyperemesis syndrome (CHS) causes some marijuana users to experience severe nausea, vomiting, and abdominal pain. A study published in the Annals of Internal Medicine found that, among study participants, 18.4% of people who inhaled cannabis and ended up in the emergency room of a Colorado hospital and 8.4% of those who ate edible cannabis and ended up in the emergency room had CHS symptoms.

CHS hasn’t been studied extensively, says Joseph Habboushe, MD, who specializes in emergency medicine at NYU Langone. While it’s possible to use marijuana for years without experiencing symptoms of CHS, once a person does experience CHS symptoms, the symptoms tend to stick around as long as the person continues using marijuana. Stopping marijuana use is the only known way to permanently alleviate CHS symptoms, but it takes time. “We know that if you stop smoking you get better, but it takes days to weeks,” Dr. Habboushe says.

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This post was originally published on June 29, 2017 and has been updated for accuracy.


Zinc lozenges do not help reduce — or shorten — symptoms of the common cold, study finds

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Zinc lozenges do not help shorten the duration of the common cold, according to a study published Tuesday in the journal BMJ Open.

In fact, taking zinc lozenges at the first signs of a cold may actually lengthen the number of days that symptoms persist, the study reports.

The study’s Finnish authors stress, however, that these findings shouldn’t be construed as the final word on whether zinc lozenges are effective against the common cold — even if they do come from a randomized controlled clinical trial (considered the gold standard of medical research).

“Our study does not confirm the usefulness of zinc lozenges for treating the common cold, but neither does it refute the previous studies where zinc lozenges were found to be effective,” says Dr. Harri Hemila of the University of Helsinki, in a released statement.

Under different conditions than those in the study — at higher doses, for example — zinc lozenges may shorten the length of a cold, he points out.

Still, the study underscores how little we really know about zinc and other popular “remedies” for illnesses like the common cold — and why we should be exceedingly cautious before using them (to protect our health as well as our pocketbooks).

Conflicting findings

As Hemila and his co-authors explain in their paper, previous research on zinc’s usefulness in treating the common cold has had conflicting results. Eight studies found zinc lozenges to be beneficial in fighting off cold symptoms, while 12 others did not.

Those differences might be due to variations in the types of the lozenges used in the studies. The researchers note that certain substances, such as citric acid, bind strongly to zinc ions, hampering the mineral’s ability to be released in the body.

For the current study, the Finnish researchers used zinc acetate lozenges. Acetate binds to zinc ions very weakly. The researchers also prescribed the zinc in daily doses of 78 milligrams, which is the amount that several previous studies with positive findings had used.

The study was conducted from Dec. 1, 2017, through April 30, 2018. Its 253 participants were employees of the city of Helsinki. All were aged 18 or older, and all said they usually had at least one cold per winter.

A package of lozenges was mailed to the participants at the start of the study. Half received zinc acetate lozenges. The others received placebo lozenges. Neither the participants nor the researchers knew which lozenges they had been given.

The participants were instructed to report back to the researchers at the first signs of a cold. They were then to immediately start taking the lozenges by dissolving six per day in their mouth and then to continue that dosage schedule for five days. During each day they were ill, the participants also filled out online questionnaires regarding their symptoms, which, of course, included sneezing, coughing, sore throat, nasal congestion, aching muscles and headache.

Key findings

Eighty-eight of the participants ended up catching a cold during the study: 46 in the zinc group and 42 in the placebo group. (A woman in the zinc group had to drop out of the study after one day, however, due to a severe reaction to the zinc.)

The study found no difference between the zinc and placebo groups in how quickly they recovered from their sneezing, coughing and other symptoms during the five days of treatment. Unexpectedly, however, people in the zinc group were more likely than those in the placebo group to have their symptoms linger for another two days.

In other words, their colds tended to last longer. The researchers say that finding needs to be confirmed or refuted in future studies.

Twice as many people in the zinc group than in the placebo group (63 percent versus 31 percent) reported side effects from the lozenges. The zinc users most commonly complained about the lozenges tasting terrible, although the taste was not bad enough, apparently, to reduce their average use of the lozenges compared to the placebo group.

Limitations and implications

The study comes with caveats. Most notably, the participants self-reported their cold symptoms. Those reports may not have accurately reflected when the symptoms started and finished. Also, the participants were not asked to return their lozenge packages, so there was no objective way of knowing whether they complied with the instructions and actually took all the pills prescribed.

Still, this was a well-designed study. At a minimum, it suggests that zinc lozenges should not be recommended for treating the common cold until more research is done.

“We found that common cold symptoms were not shortened by a commercially available zinc acetate lozenges with an instruction of 78mg/day for 5 days,” the researchers conclude.

“In future trials of the benefits and harms of commercially available zinc lozenges for common cold treatment, the lozenges should be more slowly dissolving in mouth, the dose should be over 92mg/day and the treatment should last longer than 5 days,” they add.

Of course, there’s no guarantee that even then the lozenges would work. Stay tuned.

FMI: You can read the study in full on the BMJ Open website.


Circumcision Basics

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Circumcision is the surgical removal of the foreskin, the tissue covering the head(glans) of the penis. It is an ancient practice that has its origin in religious rites. Today, many parents have their sons circumcised for religious or other reasons.

When is circumcision done?

Circumcision is usually performed on the first or second day after birth. (Among the Jewish population, circumcision is performed on the eighth day.) The procedure becomes more complicated and riskier in older babies, children, and men.

How is circumcision done?

During a circumcision, the foreskin is freed from the head of the penis, and the excess foreskin is clipped off. If done in the newborn period, the procedure takes about five to 10 minutes. Adult circumcision takes about one hour. The circumcision generally heals in five to seven days.

Is circumcision necessary?

The use of circumcision for medical or health reasons is an issue that continues to be debated. The American Academy of Pediatrics (AAP) found that the health benefits of newborn male circumcision outweigh the risks, but the benefits are not great enough to recommend universalnewborn circumcision. The procedure may be recommended in older boys and men to treat phimosis (the inability to retract the foreskin) or to treat an infection of the penis.

Parents should talk with their doctor about the benefits and risks of the procedure before making a decision regarding circumcision of a male child. Other factors, such as your culture, religion, and personal preference, will also be involved in your decision.

What are the benefits of circumcision?

There is some evidence that circumcision has health benefits, including:

  • A decreased risk of urinary tract infections.
  • A reduced risk of some sexually transmitted diseases in men.
  • Protection against penile cancer and a reduced risk of cervical cancer in female sex partners.
  • Prevention of balanitis (inflammation of the glans) and balanoposthitis (inflammation of the glans and foreskin).
  • Prevention of phimosis (the inability to retract the foreskin) and paraphimosis (the inability to return the foreskin to its original location).

Circumcision also makes it easier to keep the end of the penis clean.

Note: Some studies show that good hygiene can help prevent certain problems with the penis, including infections and swelling, even if the penis is not circumcised. In addition, using a condom during sex will help prevent STDs and other infections.

What are the risks of circumcision?

Like any surgical procedure, there are risks associated with circumcision. However, this risk is low. Problems associated with circumcision include:

  • Pain
  • Risk of bleeding and infection at the site of the circumcision
  • Irritation of the glans
  • Increased risk of meatitis (inflammation of the opening of the penis)
  • Risk of injury to the penis


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