The C-reactive protein level is an indicator of systemic inflammation that is associated with an increased risk of stroke and myocardial infarction. C-reactive protein, perhaps mediated through inflammatory factors, is elevated in patients with higher blood pressures. Sesso and colleagues conducted a study to determine whether normotensive patients with elevated C-reactive protein levels had an increased risk of developing hypertension.

Baseline blood samples were collected from participants in the Women’s Health Study and assayed for C-reactive protein. Eligible participants were healthy women without a history of hypertension. Incident cases of hypertension were identified on follow-up questionnaires.

During a median follow-up of 7.8 years, 5,365 of 20,525 women developed hypertension. There was an overall positive association between increasing levels of C-reactive protein and the risk of developing hypertension. Patients with the highest C-reactive protein levels (3.5 mg per L or higher) had a relative risk of 2.50. In women with baseline C-reactive protein levels of 1 mg per L, 1 to 3 mg per L, and more than 3 mg per L, the relative risks of developing hypertension in crude analysis were 1.00, 1.46, and 2.11, respectively. This risk was attenuated, but the pattern still held, when adjusted statistical models were applied.

The authors conclude that baseline levels of C-reactive protein are modestly but independently associated with an increased risk of hypertension. They add that this risk is associated even with patients who have very low initial systolic and diastolic blood pressures. The authors cite this finding as evidence that inflammation may play a role in the development of hypertension.