The basic principles of evidence-based medicine

Quite a lot, actually. Because the same strategy that showed that the spoon doesn't help can be used to test almost all medical interventions, by simply swapping the champagne bottle for "Medical Condition X" and the spoon for "Intervention Y." Of course, it's much harder to judge health issues than the fizziness and taste of champagne, but the principle is the same:

• There are at least two groups that can be compared to each other
• Participants' personal biases are minimized as much as possible

These kinds of tests or experiments have become normal in health care in the last 60 years. They are called randomized controlled trials (RCTs). The core idea is to, for example, test the benefits of a new medicine by dividing a group of volunteers into at least two groups by chance (“randomized”). One of the groups will use the new drug, and the other will use an older one or a placebo (dummy drug). Then the treatment outcomes and experiences of the participants are compared.

Just how these studies need to be done to deliver reliable results depends on the illness and the treatment. Sometimes, monitoring 50 or 100 people for a few weeks is enough. Other times, big studies involving several tens of thousands of men and women over many years may be necessary. What's more, single studies are often not conclusive enough to answer a research question on their own. That is why it is usually necessary to consider the results of all the relevant studies.

Today, RCTs are considered the standard for comparing treatments. This was not at all the case in the 1940s. Back then, U.S. neonatologists (experts in the care of newborn and preterm babies) had noticed that babies who were born preterm (too soon) seemed to do better if they got a lot of oxygen. Shortly after, incubators were introduced. It was now possible to keep tiny premature babies in a completely controlled environment and regulate the amount of oxygen around them. The babies' chances of survival increased dramatically.

But at the same time, people noticed that thousands of preterm babies worldwide developed a previously unknown eye disease. Nowadays this disease is called ROP (retinopathy of prematurity). The retina is the light-sensitive layer at the back of the eye. ROP can damage the retina so badly that the baby goes blind.

Nurses in England and Australia suggested it could be because of the oxygen, and published some analyses of the treatment outcomes in their hospitals. But there were many other theories too and more and more research results that contradicted each other.

Hospitals around the world started publishing reports that were supposed to show that preterm babies who were exposed to high concentrations of oxygen did not get ROP. The findings of other research groups suggested that high doses of oxygen were to blame, but couldn't provide definite answers either. In fact, none of the studies at the time were able to reliably pinpoint the cause of the condition.

In early 1953, the controversy rose to a fever pitch. By this time the mysterious disease had blinded around 10,000 infants throughout the world. Finally, the U.S. Public Health Service held a conference that resulted in 18 hospitals agreeing to participate in a randomized controlled trial for three months.

The trial results were published in 1954 and put an abrupt end to the speculation: Babies who were given very high levels of oxygen were three times as likely to develop ROP as babies who were just given a little extra oxygen. Once the research gained widespread attention, the use of oxygen in incubators was reduced around the world, putting an end to the ROP epidemic.

Because of this study, many people came to realize the importance of randomizing people in studies if their aim is to show advantages and disadvantages of a treatment.

For a long time, health care relied on doctors, experts and patients to learn what works from observation and experience. But cases like ROP have shown that, without controlled experiments, your conclusions can be very wrong when judging the advantages and disadvantages of treatments. Instead, it's important to combine science and experience, both of doctors and patients.

This basic approach is a founding principle of evidence-based medicine. “Evidence-based” means based on scientific evidence and proof. It means health care that doesn't rely only on personal views and experiences, but looks for the best verifiable evidence for the benefit of a treatment or diagnostic test. This evidence can be found in good-quality studies that examine the advantages and disadvantages.

But medical expertise and experience are also important in evidence-based medicine. In practice, a doctor has to decide whether and how available knowledge can be used in an individual patient's case. This is where experience helps. It's also important to protect patients from too much medical treatment. Good health care doesn’t mean doing "everything" for a patient, but doing the "right thing" for a patient. This helps avoid unnecessary or even harmful interventions.

Another basic principle of evidence-based medicine is to discuss the treatment options with the patient and describe the likely course of their condition if they don’t have treatment. Depending on the patient’s personal views, wishes and expectations, he or she can then make a more informed decision.

The search for clear and verifiable evidence for the effect of a treatment often doesn’t provide the clear answers you may want. One thing that often remains unclear is whether the benefits of a medical intervention outweigh its disadvantages, such as side effects or the effort involved. Although this can be unsettling, it is valuable information when deciding whether or not to have a treatment or diagnostic test.

Especially if there are no clear answers, doctors need to know the various options and their advantages and disadvantages, and openly discuss them with their patient. This enables the patient to decide for themselves what to do. A wide variety of medical and personal factors can influence this decision.