Clinical Question: Should a single elevated blood pressure reading in patients with hypertension cause concern?

Setting: Outpatient (primary care)

Study Design: Cohort (retrospective)

Synopsis: The authors of this study used an electronic medical record to identify a cohort of 5,825 patients with hypertension who were seen in 1993. They supplemented the electronic medical record with 1999 death registry data to determine whether a single elevated blood pressure reading was associated with adverse events. The outcomes of interest were acute myocardial infarction, stroke, ischemic heart disease, heart failure, kidney failure, or death from any cause. The research team identified a set of variables they thought might be associated with these outcomes and extracted them from the electronic medical record. From the pool of eligible patients, they randomly created two cohorts, one from which to derive prediction models and one for validating the models.

At the end of the five years of follow-up, 7 percent of the patients had experienced a myocardial infarction, 17 percent had a stroke, 24 percent had ischemic heart disease, 22 percent had heart failure, 12 percent had kidney failure, and 13 percent died. After controlling for other factors, the authors found that single elevations of blood pressure (systolic, mean, and diastolic) above 10 mm Hg were associated with an increased risk of adverse events.

Bottom Line: Among patients with an established diagnosis of hypertension, a single elevated blood pressure reading can predict adverse events during the next five years. More aggressive treatment may not be necessary, but this group of patients warrants close monitoring. (Level of Evidence: 1a)