What did we learn from the International Databases on Ambulatory and Home Blood Pressure in Relation to Cardiovascular Outcome?

To assess in individual-person meta-analyses how out-of-office blood pressure (BP) contributes to risk stratification and the management of hypertension, an international consortium set up the International Databases on Ambulatory (IDACO) and Home (IDHOCO) Blood Pressure in Relation to Cardiovascular Outcome. This review summarizes key findings of recent IDACO/IDHOCO articles. Among various BP indexes derived from office and ambulatory BP recordings, the 24-h and nighttime BP level were the best predictors of adverse health outcomes. Second, using the 10-year cardiovascular risk associated with guideline-endorsed office BP thresholds as reference, corresponding thresholds were derived for home and ambulatory BP. Stratified by the underlying cardiovascular risk, the rate of cardiovascular events in white-coat hypertensive patients and matched normotensive controls were not substantially different. The observation that masked hypertension carries a high cardiovascular risk was replicated in Nigerian Blacks, using home BP monitoring. The thresholds for 24-h mean arterial pressure, i.e., the BP component measured by oscillometric devices, delineating normotension, elevated BP and hypertension were <90, 90 to 92 and ≥92 mmHg. At young age, the absolute risk associated with out-of-office BP was low, but the relative risk was high, whereas with advancing age, the relative risk decreased and the absolute risk increased. Using pulse pressure as an exemplary case, the relative risks of death, cardiovascular endpoints and stroke decreased over 3-fold from 55 to 75 years of age, whereas in contrast absolute risk rose 3-fold. In conclusion, IDACO/IDHOCO forcefully support the notion that the pressing need to curb the hypertension pandemic cannot be met without out-of-the-office BP monitoring.