Expanding health insurance coverage and reducing drug costs that are paid by patients (drug co-payments) in countries without universal free healthcare, such as the United States, may improve the treatment, and control of high blood pressure (hypertension, a condition which affects one billion people worldwide and leads to 7.5 million deaths), according to a study by UK and Canadian researchers published in this week's PLOS Medicine.

Will Maimaris from the London School of Hygiene & Tropical Medicine and colleagues from the Population Health Research Institute and McMaster University in Canada reviewed 53 published studies and found an association between reduced co-payments for health care, including for medications, and improved hypertension control and treatment adherence in multiple US studies, and in studies from Finland, Israel, and Brazil.

The authors also found that in US settings, health insurance coverage and having a routine physician or place of care were linked to improved hypertension outcomes.

However, in their review, the authors found that there were few studies in low-and middle-income countries, which bear most of the global burden of hypertension, and also that there is an urgent need for studies that evaluate how aspects of health care systems other than financing (such as delivery and governance mechanisms) and interactions between health care system arrangements affect hypertension outcomes. The authors argue that without the results of such studies, governments and national and international organizations will not know the best ways to deal effectively with the global public-health crisis posed by hypertension.

The authors say: "This review supports the minimization of medication co-payments in health insurance plans, and although studies were largely conducted in the US, the principle is likely to apply more generally."

They add: "Studies that identify and analyse complexities and links between health systems arrangements and their effects on hypertension management are required, particularly in low-and middle-income countries."