This survey study followed 167 individuals without diagnosed hypertension, 2 years after a recorded systolic BP ≥ 160 mmHg and/or diastolic BP ≥ 100 mmHg at an ED visit. The main finding is that 80% of the population had measured their BP after the ED visit and one third of those had been diagnosed with hypertension. Thus, our results indicate that elevated BP during an ED visit, correlative to grade 2 hypertension levels, can reveal undiagnosed hypertension. This finding suggests the usefulness of following-up high BP after an ED visit in order to identify and treat individuals at risk.

We chose the screening cut off systolic BP value ≥ 160 mmHg and/or diastolic BP ≥ 100 mmHg as it is the defined cut off for grade 2 hypertension set by guidelines [11]. A higher cut off value, e.g. grade 3 hypertension (≥180/110 mmHg), would not be useful as those blood pressure levels, in clinical practice, generate a follow-up. A lower threshold, e.g. grade 1 hypertension (≥ 140/90 mmHg) could be a possible alternative, although it would most likely have resulted in a higher proportion of screening failure.

The current study confirms older, but smaller studies where 50-75% of patients with BP > 160/100 mmHg in the ED had BP levels indicative of hypertension using home BP monitoring [9, 12]. However, the small sample size in forementioned studies and using home BP monitoring might impact the differences with our results. Furthermore, in the current study the confirmed cases with hypertension had measured BP after the ED visit and were diagnosed with hypertension by a health-care professional. We believe that the robust form of self-reported diagnoses and reported prescription of medication is a strength in our investigation. Since we excluded patients with hypertension and/or anti-hypertensive medication our cohort showed a low percentage of other cardiovascular risk factors (only 3% had a registered history of coronary artery disease and 5% had diabetes mellitus) compared to other comparative studies [10, 13], as well as low admittance to in-hospital care (13%). Compelling, even in this “low-risk” population, subsequent hypertension was common, and our results expand earlier knowledge to this “low-risk”, unselected population.

Hypertension is highly prevalent, but up to half of the cases remain undiagnosed and not properly treated [1, 14]. Therefore, the current guidelines for the management of arterial hypertension from the European Society of Hypertension recommend opportunistic screening for hypertension in all adults [11]. However, due to limited resources in the health care system, screening young patients without risk factors does not gain wide implementation. Therefore, it is important to screen those patients when they contact the health care system, for instance at an ED visit. Elevated BP is common at the ED and depends often on the emergency context [8]. Acute pain leads to generalized increased sympathetic activity that increase the blood pressure. Transient high blood pressure per se is a pain-relieving action, possibly through increased endorphin release [15]. On the other hand, a lot of patients visiting the ED has undiagnosed hypertension that is masked in this stressful context.

Thus, using BP at the ED as an opportunistic screening for hypertension is debateable and confirming evidence of benefit are scarce. Many of the previous screening-studies do not include the ED as a potential source for screening [16]. Since measuring BP in the ED is routinely done, do not cause extra resources and is easily feasible, the ED might be a potential resource for screening. Our study shows a high rate of subsequent hypertension in patients with high BP in the ED, suggesting attention to an increased BP during an ED visit could potentially allow for earlier detection, better management, and prognosis for those patients.

Only 1% of the patients were treated with antihypertensive medication in the ED, despite a high mean BP. This might reflect the fact that physicians in the ED are not attentive to high BP or not aware of the importance of early detection of hypertension to minimize the risk for adverse cardiovascular events, including death [17].

Interestingly, we could see a high percentage of deceased patients, 12%, after two years. This is higher than reported earlier by McAllister, showing mortality rates of 3–5% within two years after an ED visit, in patients with high BP but no diagnose of hypertension [8]. However, our population were significantly older compared to that cohort, maybe explaining the surprisingly high mortality.

Some limitations in this study need to be addressed. First, the BP recorded at the ED were not standardized recording to recommendation by guidelines [11]. However, it was mainly recorded automatically, by trained nurses/assistant nurses and reflects clinical practice in an ED. Second, we lack information if the BP was taken in supine or seated position, potentially interacting with the results. Third, only 62% of the eligible patients agreed to participate in the study (167 out of the 271). This is, however, in line with positive response to previous contemporary studies [18]. Fourth, the retrospective follow-up design of the study might have affected the participation rate. In conclusion, this survey study shows that opportunistic screening at the ED of patients with BP ≥ 160/100 mmHg could within 2 years identify hypertension in one third of these individuals. This finding demonstrates the potential usefulness of BP measured at the ED as a screening instrument for hypertension.