Pre-hypertension and subclinical carotid damage: a meta-analysis

The association between pre-hypertension (pre-HTN) and subclinical carotid damage is poorly defined. We performed a meta-analysis of ultrasonographic studies assessing carotid intima-media thickness (IMT) in untreated pre-HTN subjects. The OVID-MEDLINE, PubMed, and Cochrane CENTRAL databases were searched for English-language articles without time restriction up to February 2018 through focused, high sensitive search strategies. Studies were identified by crossing the following search terms: "pre-hypertension", "high normal blood pressure", "carotid intima-media thickness", "carotid atherosclerosis", "ultrasonography". Overall, 7645 subjects (3374 normotensive, 1936 untreated pre-HTN, and 2335 HTN individuals) of both genders were included in seven studies. In the pooled study population, common carotid IMT showed a progressive increase from normotensive (723 ± 39 µm) to pre-HTN (779 ± 45 µm) (standardized mean difference, SMD 0.36 ± 0.08, CI 0.34-0.46, p < 0.0001) and to HTN subjects (858 ± 82 µm) (SMD 0.39 ± 0.07, CI 0.26-0.54, p = 0.002 vs. pre-HT). The statistical difference did not change after correction for publication bias and was not affected by a single study effect. Our meta-analysis shows that carotid IMT in pre-HTN subjects is intermediate between normotensive and HTN individuals. These findings support the view that pre-HTN is an unfavourable condition that should be properly managed in order to prevent vascular damage.