Self-measured blood pressure readings may be better predictors of cardiovascular issues or death than conventional blood pressure measurements, except among people with severe hypertension, according to a study published in the January issue of PLOS Medicine.

Kei Asayama, MD, PhD, of the University of Leuven in Leuven, Belgium, conducted a meta-analysis of more than 5,000 people not under treatment for hypertension who were randomly recruited from five populations and part of the International Database of Home Blood Pressure in Relation to Cardiovascular Outcome (IDHOCO).

“We examined to what extent self-measurement of home blood pressure (HBP) refines risk stratification across increasing categories of conventional blood pressure (CBP),” the authors explained.

They determined hazard ratios associated with 10-mm Hg increases in systolic blood pressure and categorized CBP as optimal (less than 120/less than 80); normal (120-129/80-84); high-normal (130-139/85-89); mild hypertension (140-249/90-99); and severe hypertension (160 or greater/100 or greater). CBP was measured using either an automatic or manual device and was an average of two consecutive readings at a medical facility. All participants also measured their BP at home after two to five minutes of sitting using an oscillometric device. HBP was the average of all readings.

Over an average of 8.3 years, there were 522 deaths, 414 cardiovascular events, 225 cardiac events and 194 cerebrovascular events. HRs for a composite cardiovascular outcome associated with a 10-mm Hg higher systolic BP for participants with optimal or normal CBP were 1.28 and 1.22. HRs for participants with high-normal CBP and mild hypertension were 1.24 and 1.2 for all cardiovascular events and 1.2 for stroke. HRs were not significant among participants with severe hypertension.

Masked hypertension, or HBP of 130 or greater systolic and 85 or greater diastolic, occurred in 5 percent of participants with optimal CBP, 18.4 percent of participants with normal CBP and 30.3 percent of participants with high-normal CBP. Participants with masked hypertension had a 2.3-fold higher risk of cardiovascular issues.

While the authors explained that more research is needed to determine whether the treatment of masked hypertension may protect against cardiovascular events and is cost-effective compared with current medical protocols, “these findings provide support for including HBP monitoring in primary prevention strategies for cardiovascular disease among individuals at risk for masked hypertension (for example, people with diabetes), and for carrying out HBP monitoring in people with a normal CBP but unexplained signs of hypertensive target organ damage,” they wrote.