High blood pressure is the single most important risk factor worldwide for the development of cardiovascular disease, being responsible for about half of all cases of strokes, ischaemic heart disease, and heart failure.1
High blood pressure seems to be a more powerful cardiovascular risk factor than indicated by earlier studies.2
The gains achieved by successful blood pressure control (defined as systolic blood pressure ≤140 mm Hg) have been quantified for adults in the United Kingdom.3
With an assumed reduction of 28-44% in stroke and 20-35% in ischaemic heart disease, a total of 43
000 strokes and 83
000 cases of ischaemic heart disease would be prevented in the UK annually. However, gains in health outcomes must be set against the considerable costs involved.
Over the past two decades, several countries have conducted community surveys on blood pressure detection and control. Based on national surveys, 12-25% of the population of five European countries had blood pressure above 160 mm Hg systolic or 90 mm Hg diastolic compared with 7.4% in Canada and 5.3% in the United States.4
Among these hypertensive populations, 41-52% of those in European countries were taking antihypertensive treatment compared with 62% in Canada and 78% in the US. The authors commented that European countries had higher hypertension prevalence and substantially lower treatment rates coupled with less successful control of hypertension.
In England the most recent detailed national population survey data are from the health survey for England conducted in 2003. A total of 8834 adults aged ≥16 years were surveyed with blood pressure readings taken on three occasions. Their mean blood pressure was 131/75 mm Hg. Of those with hypertension (blood pressure ≥140/90 mm Hg or taking antihypertensive drugs), 61.7% were aware of their diagnosis, 47.7% were receiving antihypertensive treatment, and 21.8% had adequate blood pressure control (blood pressure ≤140/90 mm Hg).5
In 2004 the contract for all UK general practitioners was revised to include a pay for performance system accounting for up to a quarter of total annual income. This system, termed the quality and outcomes framework (QOF), has provided new performance data aggregated at practice level.6
A total of 135 performance indicators are currently applied to each practice, measuring aspects of the structure, processes, and outcomes of primary care. Many of the performance indicators have a public health dimension, reflecting the increased public health role of primary care. Achievement of blood pressure recording for all registered patients aged ≥45 years is monitored annually. So too is the achievement of blood pressure target levels for all patients with any of five chronic conditions that are included in the QOF—hypertension, coronary heart disease, stroke and transient ischaemic attacks, diabetes, and chronic kidney disease.
The linkage of financial incentives to performance targets was intended to drive up the standards of primary care. It has also been observed that health inequalities between different population groups may be diminished as overall collective achievement increases. For example, the introduction of cervical smear targets for UK general practices in 1990 resulted in practices in affluent areas rapidly achieving the highest targets, initially widening the health inequality gap. Within a few years, however, practices in deprived areas had caught up, resulting in an eventual reduction in inequality based on social deprivation.7
This phenomenon has been termed the inverse equity hypothesis.8
In general terms, this hypothesis predicts that new public health interventions initially reach the wealthier sector of the population and then later begin to benefit the poor. In consequence, inequity ratios are initially increased, only to be diminished once the poor gain access to the intervention and a ceiling effect is reached in the richer population. Reduced QOF achievement was reported for practices in socially deprived areas in the first year of the QOF, though differences were small (6.1% of the total QOF score), but by year 2, this gap had reduced to 2.9%.9
No studies have yet reported on year 3 QOF data, and none has explored the possible association between the achievement of blood pressure indicators and social deprivation.
We decided to use the data available through the QOF to provide a current perspective on two measures—national rates of blood pressure monitoring in primary care patients and the achievement of blood pressure control targets in patients with chronic conditions. We aimed to describe changes in these two measures over the three years since QOF data have been available. In addition, we describe the effect of any changes over time on health inequalities between general practices in deprived and less deprived communities.