Rarely does tweaking a health guideline double the disease burden. It happened last week when the United States decided to lower the threshold for reading high blood pressure. By lowering it from 140/90 to 130/80, they put nearly half of American adults under the hypertensive bracket. The guideline by the American Heart Association (AHA) and the American College of Cardiology (ACC) is sweeping but has come into effect after a large study showed pretty ‘convincing’ data that markedly lower blood pressure was both beneficial and achievable.

If India, which informally follows the AHA guidelines, chooses to follow in their footsteps, it’ll nearly double the number of people under high blood pressure, from ~24% to 40% of the population. “Considering the new guideline, the same volume will be added as current hypertensive population,” says Dr Sundeep Mishra, professor of cardiology at the All India Institute of Medical Sciences in Delhi and editor of the Indian Heart Journal. “An estimated 50-60% of the adult population will come in this range (above 130/80) now. In Delhi, as many as 70% of the adult population will be hypertensive.”

That’s a whopping number given that there are 700 million adults in India, according to the 2011 census.

It’s been known for a while now that any increase in the mercury reading of blood pressure after 115 leads to a progressive increase in risks for cardiovascular diseases. But there was no study in the developed countries until the Sprint study to show it worked, says Dr Rajeev Gupta, preventive cardiologist and epidemiologist in Jaipur. “Many years ago, we showed [in a study] that Indians should have lower cut off levels. But it was more a statistical exercise than a clinical exercise,” says Dr Gupta. He runs the Jaipur Heart Watch, a long-running and the only prospective hypertension (and other cardiovascular risk-factor epidemiology) study in India with close to 10,000 people under its watch.

In India, there’s no data. And so, there are no specific guidelines.

“We only have consensus statements [from practitioners],” says Dr Gupta, who thinks the new American guideline will trigger a big debate in the country. More importantly, he fears there’ll be a push to prescribe more drugs. “There’s a temptation in India to prescribe drugs at every opportunity. But unless the reading exceeds 140, medication should be avoided,” he cautions.

That’s tough to pull off in clinics where doctors rarely have the time to seek multiple readings in different settings, a prerequisite before labelling one as a hypertensive. In addition, surveys suggest most Indians do not recognise they have hypertension, fewer get treated, and fewer still, get adequately treated because high blood pressure does not always cause symptoms. Now, with new guidelines—Europe, too, is revising its guideline next year—millions can be described as hypertensive overnight, becoming a target audience for one of the largest segments of pharmaceuticals.