Blood pressure recording bias during a period when the Quality and Outcomes Framework was introduced

Area of Science:

• Cardiovascular medicine
• Health services research
• Public health policy

Background:

• The UK Quality and Outcomes Framework (QOF) introduced financial incentives for general practitioners (GPs) to achieve target blood pressure (BP) levels (
• Understanding the impact of such policy interventions on clinical practice and patient outcomes is crucial for evaluating healthcare effectiveness.

Purpose of the Study:

• To investigate whether the introduction of the QOF BP target in 2004 influenced BP recording practices among UK general practitioners.
• To assess the true effect of QOF on patient BP control and its implications for clinical management.

Main Methods:

• Utilized the DIN-LINK GP database to extract 3,164,189 BP measurements from 236,467 patients diagnosed with ischaemic heart disease, stroke, or hypertension between 2000 and 2005.
• Assessed antihypertensive treatment using Read codes for prescriptions.
• Analyzed trends in recorded systolic BP (SBP) and diastolic BP (DBP) in relation to the 150/90 mm Hg QOF target.

Main Results:

• Recorded SBP >150 mm Hg decreased from 36% in 2000-2001 to 19% in 2004-2005.
• Observed a trend of clustering BP readings just below the 150 mm Hg threshold, with an estimated true SBP >150 mm Hg of 23% in 2004-2005.
• Patients with SBP just below the target (148-149 mm Hg) were more likely to have DBP
• Patients below the 150 mm Hg cut-off received more antihypertensive treatment (OR=1.20).

Conclusions:

• The QOF initiative has contributed to a continued fall in blood pressure levels in UK primary care, promising future public health benefits.
• The observed BP reduction was somewhat exaggerated due to data clustering below the QOF target.
• No evidence suggests adverse effects on clinical management despite the clustering phenomenon.