Previous comparative studies of Losartan and Candesartan, two drugs for treating high blood pressure, have put health service officials around the world in a serious dilemma:
There is an increased risk of death among heart-failure patients who take Losartan – which is cheap because the patent on the drug has expired – while the more expensive Candesartan is more effective. Health service officials have thus had to decide whether to prescribe the dearer Candesartan to save lives.
But making that decision is now easier thanks to a comprehensive analysis of the two types of medicine for treating high blood pressure when the patients are given comparable, medium-to-high doses.
“Contrary to previous observational studies, we cannot see any differences in this new study in the effects of the two drugs,” says Henrik Svanström, who conducts research in health statistics at the State Serum Institute. “So it doesn’t matter which drug the patient gets.”
Svanström is the lead author of a paper describing the study, published recently in JAMA, the Journal of the American Medical Association.
According to calculations made by the Institute for Rational Pharmacotherapy – a partly independent institute under the Danish Medicines Agency – the Danish public health service could have saved €67 million in 2010 alone if doctors had prescribed the cheaper Losartan to treat hypertension instead of Candesartan, which numerous patients received.
“When Candesartan and Losartan have the same effect, these results can lead to cheaper treatment for high blood pressure,” says Svanström.
The researchers studied patients over the age of 45 who had been hospitalised for heart failure in 1998-2008.
Because they suffered from heart problems, the health service registered them automatically.
The researchers then downloaded the patients’ prescriptions from the health service database to see whether the patients were treated with drugs for hypertension.
As well as the doses prescribed, this information showed that:
To make sure that they did not include patients who died from other diseases or conditions, the researchers cleansed the statistics by discounting the ordinary causes of death among heart-failure patients over the age of 45.
This statistical process showed clearly that if hypertension patients were given comparable standard doses of Losartan and Candesartan, Losartan is just as effective as Candesartan.
However, if patients were given a lower dose of Losartan (of 12.5 or 50 mg) – due to their fragile health – they do run a higher risk of dying.
Patients who were given the smallest Losartan dose of 12.5 mg had a more than two-fold increased risk of dying, compared with patients given high doses of Candesartan (16-32 mg) – presumably because their health was already more fragile.
The conclusions of previous studies may well have been correct – but those studies did not contain enough nuances, says Svanström.
His research team claims that the new study is more thorough than previous studies that have compared the two drugs for treating high blood pressure.
“The population in our study has a better composition,” says Svanström. “We have a better balance of doses. Our study has a higher share of Losartan-users who received a high dose. And that was what made the pattern visible to us.”
Read this story in Danish at videnskab.dk