medwireNews: A long follow up of a large sample of community-based patients with diabetes suggests that the current guideline blood pressure targets may be too low.
The researchers found a U-shaped relationship between baseline blood pressure and outcomes up to 11 years later, with a nadir at a systolic blood pressure of 135 mmHg for cardiovascular events and 142 mmHg for mortality among patients not taking antihypertensive drugs.
"These new values of the [blood pressure] at which the risk of events is lowest are important and should impact on future guidelines for treatment targets for [blood pressure] in patients with diabetes, as they are considerably higher than targets in many current guidelines," writes Peter Sleight (John Radcliffe Hospital, Oxford, UK) in an editorial accompanying the study in the Journal of Hypertension.
He observes that the study "is more representative than the prior data which has usually been solely from hospital practice."
The 34,009 diabetes patients in the study were drawn from 84 primary care centers in Sweden. All were aged at least 35 years and free of overt cardiovascular disease at the start of follow up, during which 18.7% of patients had a first cardiovascular event and 18.3% died.
A U-shaped association was also evident for patients who were taking antihypertensive drugs, and the nadir systolic blood pressures were similar, at 139 mmHg for cardiovascular events and 150 mmHg for mortality.
The associations held when the researchers, led by Johan Sundström (Uppsala University, Sweden), attempted to exclude reverse causality (ie, cardiac damage affecting blood pressure) by reducing the analysis to 25,744 patients who did not have an outcome event until at least 2 years after baseline.
Assuming a 50% increase in cardiovascular event risk to be clinically relevant, such an increase occurs at above 181-185 mmHg and below 107–114 mmHg, says the team.
In his editorial, Sleight cautions that "we need proper data from randomized trials" to be confident of treating to higher targets, and notes that one such study is in progress. "In the mean time, the study by Sundström et al adds to the evidence suggesting some caution regarding untested lower targets for blood pressure in patients with diabetes."
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