Could self-measured office blood pressure be a hypertension screening tool for limited-resources settings?
Blood pressure (BP) was assessed by patients themselves in recently published trials. Self-measured office blood pressure (SMOBP) seems particularly interesting for limited health resources regions. The aim of our study was to evaluate the relationship between SMOBP values and those estimated by ambulatory blood pressure monitoring (ABPM). Six hundred seventy-seven patients were evaluated using both, SMOBP and ABPM. The differences between SMOBP and daytime ABPM were evaluated with paired "t" test. The correlations among SMOBP and ABPM were estimated using Pearson's r. The accuracy of SMOBP to identify abnormal ABPM was determined using area under ROC curve (AUC). Sensitivity, specificity, and positive and negative predictive values were calculated for different SMOBP cut-points. Using the average of three readings, systolic SMOBP was higher (3.7 (14.2) mmHg, p < 0.001) and diastolic SMOBP lower (1.5 (8.1) mmHg, p < 0.001) than ABPM. Both BP estimates had a significant correlation, r = 0.67 and r = 0.75 (p < 0.01) for systolic and diastolic BP, respectively. Systolic SMOBP predicted systolic abnormal ABPM; the AUC were 0.80 (0.77-0.84) and 0.78 (0.74-0.81) for daytime and 24 h hypertension, respectively. Diastolic SMOBP predicted diastolic hypertension, AUC 0.86 (0.83-0.88) for both daytime and 24 h hypertension. Neither correlations nor AUCs improved significantly using the average of five readings. SMOBP ≥ 160/90 mmHg was highly specific (>95%) to identify individuals with hypertension in the ABPM; SMOBP < 130/80 mmHg reasonably discarded abnormal ABPM. In conclusion, a high proportion of individuals could be classified adequately using SMOBP, reducing the necessity of healthcare resources and supporting its utility for screening purposes.