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QUESTION: Do diastolic blood pressure (BP) and other risk factors predict the development of hypertension in people who are not receiving hypertension treatment at baseline?
Design
Prospective cohort study of men and women in the Nijmegen Cohort Study with 18-year follow-up.
Setting
6 general practices in the Netherlands.
Participants
2238 men and women (mean age 35 y, 52% men, 100% white) who were not receiving hypertension treatment at baseline.
Assessment of risk factors
BP, age, familial cardiovascular risk factors, smoking status, physical activity, weight, body mass index (BMI), serum cholesterol level, socioeconomic status, and history of diabetes were measured at baseline. BP, familial risk factors, smoking status, weight, and serum cholesterol level were measured after 18 years of follow-up. Outcome assessors at follow-up were blinded to the baseline data.
Main outcome measures
Hypertension was defined in 2 ways: current hypertension treatment or diastolic BP ≥ 95 mm Hg.
Main results
Regression analysis in women showed that the risk for developing hypertension was associated with baseline diastolic BP (p<0.005), weight gain (p<0.005), and baseline BMI (p<0.05). In men, the risk for developing hypertension was associated with baseline diastolic BP (p<0.005) and weight gain (p<0.005) and was inverselyassociated with socioeconomic status (p<0.05). The table shows the risks for developing hypertension as determined by baseline diastolic BP and weight gain. Women had greater increases in hypertension risk with increasing baseline diastolic BP and weight gain than did men.
Relative risks (RRs) for developing hypertension as determined by baseline diastolic blood pressure and weight gain in men and women at 18-year follow-up
Conclusion
Diastolic blood pressure and weight gain predicted the 18-year risk for hypertension in men and women who were not receiving hypertension treatment at baseline.
Commentary
Several methodological issues in the prospective cohort study by Bakx and colleagues should be noted. The initial evaluation used 2 BP measurements during only 1 visit and used 2 different cuff sizes. For the final screening, however, 1 cuff size was used despite evidence that this variation could result in a systematic difference. At least 12% of the initial population had hypertension by the diastolic BP criteria but remained in the study because they were not being treated. Furthermore, patients who died between the screenings were not discussed. Despite these issues, however, the conclusions reinforce what has been found in other studies1, 2: Weight gain and baseline BP are predictive of the development of hypertension, especially in women.
What is the clinical utility of this information? The authors suggest that BP measurements should be done regularly in patients with diastolic BP >80 mm Hg who gain weight. Alternatively, for those with diastolic BP <75 mm Hg, the authors maintain that measuring BP every 2 years may be unnecessarily time consuming. The first recommendation is reinforced by other longitudinal studies, but the second cannot be supported by these data because of the methodological issues mentioned above. Given the low cost and non-invasive nature of BP measurement, screening for hypertension should still be recommended every other year for the early detection of this important risk factor.
Footnotes
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Source of funding: The Netherlands Heart Foundation.
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For correspondence: J C Bakx, Department of General Practice, University of Nijmegen, 229 HSV, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands. FAX +31-24-3541862.
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A modified version of the abstract and commentary also appears in Evidence-Based Nursing