Cardiovascular risk prediction based on home blood pressure measurement: The Didima Study

OBJECTIVE: Although home blood pressure (HBP) is being used increasingly in clinical practice, the evidence on its prognostic value is still limited. This study in the general population investigated the value of HBP compared to office measurements (OBP) in predicting cardiovascular risk. SUBJECTS AND METHODS: In 1997 all adults of the Didima area in Greece were invited to participate in a cross-sectional study involving OBP (two visits) and HBP measurements (3 days). Incident cardiovascular morbidity and cause-specific mortality were assessed after 8.2 +/- 0.2 years (mean +/- SD). Average OBP and HBP were used in Cox regression analysis of fatal and non-fatal cardiovascular events with age, gender, history of cardiovascular disease, use of antihypertensive medication, smoking and diabetes as covariates. RESULTS: A total of 662 subjects were analysed (mean age at baseline 54.1 +/- 17.6 years). During follow-up 78 deaths (42 cardiovascular) and 67 cardiovascular events (fatal and non-fatal) were documented. Unadjusted hazard ratios for cardiovascular events per 1 mmHg blood pressure increase were for HBP systolic 1.034 (P < 0.001) and diastolic 1.037 (P < 0.01) and for OBP systolic 1.035 (P < 0.001) and diastolic 1.021 (P = 0.07). After adjustment for all available cardiovascular risk predictors, only diastolic OBP remained significant. The addition of HBP in the models already including OBP did not significantly improve the predictive ability. White coat but not masked hypertensives were at high risk. CONCLUSIONS: This study showed that both HBP and OBP are significant predictors of cardiovascular risk in the general population. However, no prognostic superiority of HBP compared to OBP has been demonstrated.