Original Articles
Cardiovascular Morbidity and Mortality Among Hypertensive Patients in General Practice: The Evaluation of Long-Term Systematic Management

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Abstract

Objective: To evaluate systematic management of hypertensive patients with regard to cardiovascular morbidity and mortality. Design: In a matched cohort study (1978–1993) the number of cardiovascular events among hypertensive patients under continuous systematic management in four general practices was compared with those occurring among hypertensive patients from eight “usual care” general practices. Subjects: The source population consisted of employees of a major electronic company in Eindhoven with hypertension as determined at an occupational health examination. The index group (n = 120) consisted of employees who were participating in the systematic management program in four practices. A reference group of 120 patients was selected from hypertensive employees who were registered in eight “usual care” practices by matching for age, gender, fasting blood glucose, and frequency of occupational health examinations. The total cohort consisted primarily of males (78%), whose ages ranged from 50 to 65 years. Main outcome measures: Risk difference (RD) per 1000 patient years regarding left ventricular hypertrophy, heart failure, angina pectoris, myocardial infarction, transient ischaemic attack, stroke, peripheral arterial disease, nephropathy, retinopathy, cardiac death, death due to stroke, and non-cardiovascular death was determined. In addition to morbidity and mortality, systematic hypertension management was evaluated with regard to cardiovascular risk factors throughout a period of maximally 12 successive years (1978–1989). Morbidity and mortality data were derived from general practice records and archives; data on risk factors were assessed at bi-annual occupational health examinations. Results: The total follow-up duration amounted to 2628 patient years. The mean follow-up duration in the index group was 10.8, in the reference group 11.1 years. As compared to the “usual care” reference group, the index group showed less left ventricular hypertrophy (RD 8.2, 95% CI 1.4–15.0), less angina pectoris (RD 9.7, 95% CI 2.0–17.4) and less peripheral arterial disease (RD 3.7, 95% CI 0.5–7.1). The difference in mean decrease in blood pressure during follow-up was 11.3 mmHg systolic and 5.9 mmHg diastolic in favour of the index group. No significant differences between the index and the reference groups were found with regard to the changes in other risk factors. Conclusion: In our study systematic management of hypertensive patients aged 50 to 65 in general practice was associated with a statistically significant, and clinically relevant decrease in cardiovascular morbidity and blood pressure. Although causality cannot be determined from this non-randomized cohort study, the findings do support the view that systematic management of hypertensive patients in general practice is valuable.

Introduction

Hypertension is one of the principal risk factors associated with cardiovascular disease 1, 2. The success of short-term interventions with drug treatment in hypertensive patients has already been shown convincingly [3]. Interestingly, the most spectacular results of these studies were obtained among elderly [4]. However, the outcome of systematic management of hypertensive patients in general practice has been studied much less, and long-term studies in this field in particular are rare.

General practitioners (GPs) in The Netherlands are in a good position to implement prevention of cardiovascular disease, as are those in the United Kingdom 5, 6. The continuity of care, the fixed practice list of Dutch GPs, and the low threshold on the part of patients to consult GPs give them the opportunity to detect, treat, and follow patients who have a high risk for cardiovascular diseases. Systematic management involves surveillance and treatment of several risk factors, as well as of established cardiovascular disease.

In 1978, four general practitioners in Eindhoven (The Netherlands) started a systematic hypertension management program, including detection, treatment, and long-term management of hypertension. Systematic registration of patient data was an essential element of this program. As a substantial number of patients were employees of a local major electronic company with periodic occupational health examinations, also independent and standardized data on these patients are available. Because this company is the major employer in the region, it was also possible to identify a large reference group of hypertensive patients who were not registered in these four practices. This unique situation has led us to examine the following questions: (i) Are there differences in cardiovascular morbidity and mortality between hypertensive patients under systematic management and hypertensive patients under usual general practice care? (ii) What are the differences in time course of cardiovascular risk factors between both groups?

Section snippets

Design

This article reports on a follow-up study among two subcohorts: an index and a reference group of hypertensive patients. The index group was characterized by participation in a systematic management program for hypertensive patients. The reference group receiving “usual care” for hypertension was established by matching. The number of cardiovascular events and the time course of cardiovascular risk factors was compared between these two groups. Cardiovascular events were measured over the

Comparability of the Index and the Reference Group

Table 1 shows the baseline characteristics of the two groups. The mean duration of hypertension was 4.5 years for the index group, and 3.4 years for the reference group. Substantial differences between the two groups were found for SES, family history of hypertension, baseline blood pressure, and GFR. The baseline blood pressure was clearly higher in the index group (164/103 SBP/DBP mmHg) than in the reference group (148/95 SBP/DBP mmHg). The reference group consisted of more patients of high

Discussion

This cohort study demonstrates that more than 10 years of systematic management of hypertensive patients, i.e., systematic treatment and follow-up in general practice, is associated with lower cardiovascular morbidity rates as compared with usual care, as well as with a larger decrease in systolic and diastolic blood pressure in patients aged 50 to 65 years. Unlike blood pressure, the differences between the index and the reference groups with regard to other risk factors such as increased

Acknowledgements

The authors thank Mrs. D. Kriegsman, M.D., Ph.D. for her help in carrying out the survival analysis.

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