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Defining hypertension in older people from primary care case notes review
S Duggan1, M J Aylett, M Eccles
1Centre for Health Services Research, University of Newcastle Upon Tyne, UK.
Insights
A new method accurately defines hypertension using primary care records. This approach aids in studying hypertension management and research in general practice.
Area of Science:
- Cardiology
- General Practice
- Health Informatics
Background:
- Accurate identification of hypertension in primary care is crucial for effective patient management.
- Primary care patient records offer a rich data source for epidemiological studies.
- Existing methods for defining hypertension status from records may have limitations.
Purpose of the Study:
- To develop and validate a method for defining blood pressure (BP) status using primary care patient records.
- To assess the accuracy of this method in identifying hypertensive and normotensive patients.
- To determine the utility of primary care data for hypertension research.
Main Methods:
- A flowchart-based method was developed using BP measurements, medication, and comorbidities.
- The method was validated against a general practitioner's assessment using 6 years of data from patients aged 65-80.
- Sensitivity and specificity were calculated, and the impact of including a hypertension diagnosis was evaluated.
Main Results:
- The developed method showed a sensitivity of 86% and specificity of 88%.
- Including the recorded diagnosis of hypertension improved sensitivity to 98% with unchanged specificity.
- Disagreements between the method and practitioner occurred in 11% of cases, with identifiable reasons.
Conclusions:
- Primary care case notes provide a valid and accessible means for defining hypertension cases.
- This method supports research into hypertension management within primary care settings.
- The accuracy of case definition is influenced by the quality of recorded hypertension diagnoses.
Abstract:
A method of defining blood pressure (BP) status from a review of primary care patient records was developed and then validated using the case notes of a general practitioner with an interest in hypertension. Data were drawn from the records of the previous 6 years of all 65 to 80-year-old patients in the practice (n = 263). Patients were then categorised as hypertensive, normotensive or 'undetermined' by using a flowchart based on the mean of the three most recent BP measurements, antihypertensive medication and comorbidities of ischaemic heart disease, myocardial infarction, angina, oedema or cardiac failure. Mean systolic BP of > or = 160 mm Hg and/or diastolic BP of > or = 90 mm Hg were used as a threshold definition of hypertension and of BP control. Disagreement between general practitioner and the notes based definition occurred in 11% of patients (5% hypertensive, 6% normotensive). Reasons for disagreement were: controlled hypertensives with comorbidities such as angina or heart failure (4%), isolated elevated readings (3%), use of antihypertensive medication for separate indications (2%), other reasons (2%). The resulting sensitivity and specificity was 86% and 88% respectively. Including the recording of a diagnosis of hypertension in the definition increased the sensitivity to 98% with specificity unchanged at 88%. Actual sensitivity of the instrument when used in other practices is likely to lie between 88% and 98% depending on the quality of the doctor's recording of the diagnosis of hypertension. These findings suggest that data from primary care case notes can provide a ready and valid means of defining cases of hypertension for studying the management of hypertension in primary care and for research purposes.