Lancet-published calculator shows how medications impact blood pressure

Hyderabad: A new online tool that calculates how different medications lower blood pressure could change how hypertension is treated worldwide.

The Blood Pressure Treatment Efficacy Calculator, published on Friday in The Lancet, uses data from nearly 500 randomised clinical trials involving over one lakh people.

Evidence-based tool for treatment

The calculator enables doctors to select treatment based on how much a patient’s blood pressure needs to be reduced, rather than relying only on variable blood pressure readings.

“This is really important because every 1 mmHg reduction in systolic blood pressure lowers your risk of heart attack or stroke by two per cent,” said Nelson Wang, cardiologist and Research Fellow at The George Institute for Global Health.

“But with dozens of drugs, multiple doses per drug and most patients needing two or more drugs, there are literally thousands of possible options and no easy way to work out how effective they are,” he added.

Relevance in India

Speaking about the research, Dr Mohammad Abdul Salam, Program Head, Cardiovascular Research, The George Institute for Global Health, Hyderabad, said: “We cannot overlook the importance of controlling high blood pressure effectively and efficiently. Achieving optimal control requires a clear understanding of the efficacy of antihypertensive drugs at different doses and in various combinations. Without clarity on what we want to achieve and how to achieve it, we will not meet our targets. Guidelines define the target blood pressure, while our online tool helps identify which antihypertensive drugs are best suited to reach that target.”

Comparing the efficacy of treatments

The tool calculates the average treatment effect across hundreds of trials and categorises medications as low, moderate or high intensity. This approach mirrors methods already used in cholesterol treatment.

A single antihypertensive medication lowers systolic blood pressure by about 8–9 mmHg. However, most patients require reductions of 15–30 mmHg to reach ideal targets.

Dr Wang explained that measuring blood pressure directly to judge treatment efficacy is unreliable: “Blood pressure changes from moment to moment, day to day and by season – these random fluctuations can easily be as big or larger than the changes brought about by treatment. Also, measurement practices are often not perfect, bringing in an additional source of uncertainty. This means it’s very hard to reliably assess how well a medicine is working just by taking repeated measurements.”

Moving beyond ‘Start Low, Go Slow’

Anthony Rodgers, Senior Professorial Fellow at The George Institute for Global Health, said that despite hypertension being the most common reason people visit a doctor, no comprehensive resource has existed until now.

“Using the calculator challenges the traditional ‘start low, go slow, measure and judge’ approach to treatment, which comes with the high probability of being misled by BP readings, inertia setting in or the burden on patients being too much,” he said.

“With this new method, you specify how much you need to lower blood pressure, choose an ideal treatment plan to achieve that based on the evidence, and get the patient started on that ideally sooner rather than later.”

The next step will be to test the tool in clinical trials, prescribing treatments guided by the calculator.

A global health challenge

High blood pressure affects an estimated 1.3 billion people worldwide and contributes to around 10 million deaths annually. It is often called a ‘silent killer’ as it shows no symptoms until it results in serious complications such as a heart attack, stroke or kidney disease.

Fewer than one in five people with hypertension have the condition under control.

“Given the enormous scale of this challenge, even modest improvements will have a large public health impact, increasing the percentage of people whose hypertension is under control globally to just 50 per cent could save many millions of lives,” Professor Rodgers added.

Accessing the tool

The Blood Pressure Treatment Efficacy Calculator is available online at www.bpmodel.org. The full study is published in The Lancet.