Blood pressure is a key risk factor for coronary heart disease. Levels are declining in many industrialised countries, but the mechanism is not known.
There are two possible patterns of blood pressure fall in the population. In one, doctors target people with high readings for treatment, leaving others alone. The other, mass population change (from diet, lifestyle or, environmental factors) sees falls in middle and low readings as well. Both change the population average.
So did blood pressure fall from mass population change, or was it pushed down by drugs?
To answer this question, researchers analysed patterns of blood pressure decline, pooling results collected across 38 populations in 21 countries from the mid-1980s to mid-1990s in the World Health Organisation MONICA (monitoring) study.
Averaged results from the 38 populations showed that blood pressure fell equally at all levels of readings. So, better antihypertensive medication made no detectable contribution to the population decline in blood pressure in the mid-1980s to mid-1990s, say the authors.
They suggest that determinants of blood pressure decline other than medication must have been more pervasive and powerful in the population as a whole during that decade but they cannot say exactly what these were.
These findings do not deny the importance of antihypertensive medication in the individual, but are important in understanding blood pressure as a challenge to public health, they conclude.