Selective recording in blood pressure readings may increase subsequent mortality
D Wingfield1, G K Freeman, C J Bulpitt
1Department of Primary Health Care and General Practice and. Section of Care of the Elderly, Imperial College, Faculty of Medicine, London, UK. david@hammerpcg.org.uk
Insights
Blood pressure measurement biases, like number preference, can affect hypertension screening accuracy. This study found that a diastolic blood pressure reading of 88-89 mmHg in women was associated with increased cardiovascular and all-cause mortality compared to 90-99 mmHg.
Area of Science:
- Cardiology
- Clinical Epidemiology
- Biostatistics
Background:
- Blood pressure (BP) measurement inaccuracies, such as terminal digit preference and number preference, are known issues.
- These biases can compromise diagnostic accuracy and potentially impact patient treatment and survival outcomes.
Purpose of the Study:
- To investigate number preference in hypertension screening.
- To determine if this preference influences subsequent mortality rates.
Main Methods:
- A prospective case-control screening study was conducted within the General Practice Hypertensive Study Group (GPHSG).
- 23,574 patients were screened for high phase-IV diastolic BP (DBP4) (≥90 mmHg), with cases matched to normotensive controls.
- Mortality follow-up was established for 6,310 patients.
Main Results:
- A significant over-representation of the terminal digit '0' (28.2% vs. 20%) and the number '88' for DBP4 was observed in both sexes.
- Females with DBP4 of 88-89 mmHg showed significantly higher cardiovascular (RR 2.56) and all-cause mortality (RR 1.56) compared to those with 90-99 mmHg.
- Males exhibited non-significant reductions in mortality rates.
Conclusions:
- The study highlights the impact of BP measurement biases on clinical outcomes.
- Monitoring BP measurement quality in research and clinical practice is crucial for accurate diagnosis and effective patient management.
Background:
Rounding blood pressure (BP) to the nearest 10 mmHg (terminal digit preference) and selecting for particular values near treatment cut-offs (number preference) have both been previously described. Both reduce measurement accuracy, and may have consequences for treatment and survival.
Aim:
To check for number preference in screening for hypertension, and whether this influenced subsequent mortality.
Design:
Prospective case-control screening study.
Methods:
In the General Practice Hypertensive Study Group (GPHSG), prospective case control study patients (n=23 574) were screened on one occasion for high phase-IV diastolic BP (DBP4) (> or =90 mmHg). Identified cases were matched with normotensive controls for age, sex, date of screen and ethnic group, and were registered for mortality follow-up (n=6310). Patients with a high DBP4 had two further readings, and were treated if it remained elevated.
Results:
For DBP4 terminal digit, '0' was over-represented (28.2% vs. 20%), and the number '88' was over-represented in both men and women. There was an excess adjusted death rate for females with DBP4 88-89 mmHg vs. 90-99 mmHg for both cardiovascular (RR 2.56, 95%CI 1.43-4.56, p=0.0015) and all-cause (1.56, 95%CI 1.06-2.29, p=0.023) mortality. For males, the corresponding rates were non-significantly reduced: cardiovascular RR 0.69, 95%CI 0.42-1.14, p=0.15; all-cause RR 0.93, 95%CI 0.68-1.27, p=0.64.
Discussion:
The quality of BP measurements should be monitored both in research studies and in clinical practice as part of clinical governance procedures.
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