Lower salt trumps other lifestyle changes in combatting high blood pressure, UCSF model shows

Imagine a visit to the doctor where you received news that you had an early form of a deadly disease. To stop the disease from progressing, you would need to drink less, exercise more, eat a healthy diet full of fruits and vegetables, cut back on salt, and lose weight. You’d probably walk away wondering where to start, which suggestion was most important, and just how big your changes would have to be to make a difference.

This is what happens to roughly a quarter of adults in the United States when they are diagnosed with stage 1 hypertension, the less severe of two tiers of high blood pressure. High blood pressure might sound less dramatic than cancer, but it is a major risk factor for heart attacks and strokes, the biggest killers in the developed world.

According to work presented by postdoctoral fellow Kendra Sims, PhD, at an American Heart Association conference in San Diego on September 10, a healthy low-salt diet is the heaviest hitter on the laundry list of lifestyle changes that doctors recommend for patients with stage 1 hypertension. The research specifically considered the DASH diet, which is a fairly standard healthy diet that also limits salt.

The researchers estimated that 8.7 million U.S. adults aged 35-64 have stage 1 hypertension for which medication is not indicated. Many may not even know because the definition of hypertension was expanded in 2017. Waving a magic wand such that all of these Americans followed the DASH diet and didn’t make any of the other changes would eliminate 26,000 adults from developing cardiovascular disease – including angina, heart attack, and stroke – by 2027, the researchers found. It would also save the healthcare system upwards of $1.7 billion. In comparison, increasing exercise or decreasing drinking in the absence of other changes would have smaller, though not insignificant, effects.

“Our results show that large-scale, healthy behavior modifications would prevent future heart disease and related complications,” Sims said. “Of course, these changes would not be free. We might have to subsidize people’s diets, improve food deserts, change which crops we subsidize from meat and sugar to fruits and vegetables, or put a cap on how much sodium can go into processed foods.”

The research draws on a sophisticated computer simulation based at UCSF, called the Cardiovascular Disease Policy Model. The first paper using the model was published in 1987, and since then oversight of the model passed from Lee Goldman, MD, to Kirsten Bibbins-Domingo, MD, PhD, MAS.

“The model is a basic platform on which you can ask a number of questions,” said Joanne Penko, MS, MPH, who serves as what may best be described as the model’s handler. (Pamela Coxson, PhD, is the model’s maker.) “Over the years we’ve incorporated more and more complexity as more resources and source data became available.”

The model simulates cardiovascular disease over time with and without specific interventions, Penko explained. It uses Census data to create a hypothetical version of every U.S. resident over the age of 35, and assigns them, based on the most reputable national health datasets, to risk factors such as smoking and diabetes. It then uses cohort data, meta-analyses, and clinical trial outcomes to posit an appropriate number of cardiovascular events each year over the next decade, as risk factors come home to roost as the hypothetical people age. It draws on representative hospital and healthcare cost databases to model the costs.

What if all the smokers magically stopped smoking? The model moves these people from light or heavy smoking groups into the nonsmoking group, lowering their risk, and consequently the number of cardiac incidents, every year thereafter.

The model is especially useful for measuring what would happen if everyone were equally able to obtain and follow the best available medical advice – which is, unfortunately, not what happens in our chaotic healthcare system.

“We know that marginalized people tend not to benefit from a lot of these recommendations and guidelines,” Sims said. “A lot of them don’t have regular healthcare access, which means they may not get the advice in the first place. And work schedules and lack of access to affordable fruits and vegetables or parks or gyms may make it impossible for folks to eat better and exercise. A lot of the recommendations really only make sense for the middle class.”

Indeed, according to the study, just 61% of people with stage 1 hypertension have regular access to healthcare.

Sims’s simulation proves that there are people whose lives could be saved with policy interventions, she said. And if lives aren’t enough to persuade policymakers, maybe the financial savings can.