At ERH Associates, we often talk about practising evidence-based medicine. But what does that actually mean…in practice?

Evidence-based medicine (EBM) is about using the best available scientific research to guide our decisions, combined with our clinical expertise and your needs, values and preferences. It’s a commitment to starting from what’s been shown to be safe and effective, rather than being influenced by trends, anecdotes, or marketing claims.

Why Evidence Is Our Starting Point

High-quality research — such as large, well-designed clinical trials and systematic reviews — gives us confidence in both safety and effectiveness. It helps us avoid treatments that sound promising but may not work, or worse, could cause harm.

But here’s the reality: we don’t yet have strong research for everything we want to know about the human body and how to keep it well. Some questions simply haven’t been studied yet, or the studies are too small, too narrow, or poorly designed (with potential for confounding factors, for example) to give definitive answers.

Risk Matters: When We Need Strong Evidence vs When We Don’t

When a treatment is potentially very toxic or harmful, we must be extremely careful. This is where the principle of first, do no harm — a core part of the Hippocratic Oath that doctors take — comes into play. If the risks are high, we only use it in situations where there’s strong evidence that the benefits outweigh the risks — and even then, under close supervision.

For example, chemotherapy drugs can be life-saving for certain cancers but are highly toxic, so their use is justified only when the expected benefits clearly outweigh the potential harms.

Another example: the use of Menopausal Hormone Therapy (MHT) in people with a history of breast cancer is an area with very limited safety data [1–4]. Because the potential outcome is serious (breast cancer recurrence or faster growth of residual cancer), endocrinologists are generally very cautious about prescribing MHT in this setting. Decisions are highly individualised, weighing up factors such as:

• The level of theoretical risk for that individual
• Severity of symptoms
• Impact on quality of life
• Availability of safer alternatives

Sometimes, if symptoms are severe and the safest options have not helped, a person may choose to accept a certain level of uncertainty — but this should always be done under the guidance of a specialist who is up-to-date with the evidence and who will regularly reassess whether the treatment is still needed and whether benefits continue to outweigh risks.

On the other end of the spectrum are low-risk approaches. For example, one study has shown that being around flowers can improve mood [5]. But even if you didn’t know this study existed, there’s no reason to suspect harm from looking at flowers (unless you have severe allergies and get too close!).  That means we don’t need a large body of evidence to say: “If you love flowers and feel they boost your mood, go right ahead and enjoy them!”

The strength of evidence needed always depends on the balance between potential benefit and potential harm.

Where the “Art” of Medicine Comes In

When the evidence base is incomplete, doctors still need to make decisions. This is where the “art of medicine” matters.

We start with the data we do have, then aim to extrapolate in a way that is safe and scientific — personalising treatment for each individual. Different doctors might interpret the same evidence in slightly different ways. That doesn’t automatically mean one is right and the other wrong; it’s often about different starting points, experiences, or approaches to balancing benefits and risks.

A Practical Example
Consider MHT or thyroid hormone replacement.
We know from research:

• What these treatments can do
• Typical starting doses
• Target ranges for blood tests

But each person’s response is unique. Two people with the same symptoms or blood results can react very differently. That’s why treatment often involves:

• Starting at a safe, reasonable point (which may differ between doctors)
• Monitoring your response — both symptoms and lab results
• Adjusting as needed until we find the regime that works for you

Two doctors might begin in very different places but, through this process, but may end up in a similar place — ideally with you feeling well and your doses at a safe level.

Why This Matters

Evidence-based medicine isn’t about being rigidly bound to the outcomes of studies, nor is it about ignoring science when there’s uncertainty. It’s about:

• Starting with the strongest, most reliable evidence we have
• Taking into consideration the strength of evidence needed based on the potential risks and benefits
• Applying findings with clinical expertise and judgement

Personalising care to your needs, values, and circumstances

• Monitoring your response and adjusting accordingly
• Reassessing regularly to ensure treatments remain appropriate

In a nutshell, evidence-based medicine is science as the foundation, with the art of medicine bridging the gaps to shape how that science works for you.

And that’s why you’ll often see our Myth Busting Series challenge popular “quick fixes” or trending health advice. If something’s being sold as a sure thing but doesn’t have the evidence to back it up — or the risks outweigh the potential benefits — we’ll tell you why, and help you figure out what is worth your time, energy, and money.

References:

Haviland-Jones J, Rosario HH, Wilson P, McGuire TR. An environmental approach to positive emotion: Flowers. Evol Psychol. 2005;3(1):104–132.

Holmberg L, Anderson H; HABITS steering and data monitoring committees. HABITS (hormonal replacement therapy after breast cancer—is it safe?), a randomised comparison: trial stopped. Lancet. 2004;363(9407):453–455.

Fahlén M, Fornander T, Johansson H, et al. Hormone replacement therapy after breast cancer: 10-year follow-up of the Stockholm randomised trial. Eur J Cancer. 2013;49(1):52–59.

Cold S, Cold F, Jensen M-B, Cronin-Fenton D, Christiansen P, Ejlertsen B. Systemic or vaginal hormone therapy after early breast cancer: a Danish observational cohort study. JNCI. 2022;114(10):1347–1354.

Marchetti C, De Felice F, Boccia S, Sassu CM, Di Donato V, Perniola G, Musella A, Palaia I, Tombolini V, Muzii L, Benedetti Panici P. Hormone replacement therapy after prophylactic risk-reducing salpingo-oophorectomy and breast cancer risk in BRCA1 and BRCA2 mutation carriers: a meta-analysis. Crit Rev Oncol Hematol. 2018;132:111–115.