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The intervention effects of a community-based hypertension control programme in two rural South African towns: the CORIS study
Abstract
The objective of the hypertension programme of the Coronary Risk Factor Study (CORlS) was to evaluate the effectiveness of the first 4 years of community-based intervention. The hypertension intervention model comprised a blood pressure station where the whole population was screened for hypertension, non-drug management was provided and hypertensives were monitored after referral to general practitioners for drug therapy. Two levels of intervention were maintained: in the high-intensity intervention town (N =2 278) hypertensives were actively followed up, and in the low-intensity intervention town (N =2 620) no active follow-up procedure existed. A third town acted as control (N= 2 290).
In the cohort which was hypertensive at baseline, the net decreases in systolic blood pressure (mean ± SE) after correction for changes in the control town were 0,5 ± 2,2 mmHg (men) and 4,5 ± 2,2 mmHg (women) in the low-intensity intervention town, and 5,6 ± 2,3 mmHg (men) and 7,5 ± 2,2 mmHg (women) in the high-intensity intervention town. The net decrease in diastolic blood pressure was 3,4 ± 1,2 mmHg (men) and 4,4 ± 1,1 mmHg (women) in the low-intensity intervention town, and 6,1 ± 1,2 mmHg (men) and 5,9 ± 1,1 mmHg (women) in the high-intensity intervention town. These reductions were statistically significant with one exception. The changes in the total population in the 3 communities after 4 years of intervention were similar to those found in the hypertensive cohort.
Decreases in mean blood pressure were accompanied by marked increases in the proportion of hypertensives on drug treatment and the proportion under control (< 160/95 mmHg).
Distribution curves of blood pressure indicated a large effect in the subgroup above the cut-off point for hypertension; however, the entire curve also shifted to the left, indicating, in addition, benefit to the whole population. An increase in the appropriate knowledge and action for hypertension control was observed in the intervention towns compared with the control town.
The CORlS community-based hypertension control programme successfully reduced the risk for cardiovascular diseases in the intervention towns compared with the control town.