Isolated clinic hypertension: Diagnostic criteria based on 24-h blood pressure definition

Objective The use of diagnostic criteria based on 24-h ambulatory blood pressure (BP) values could improve prognostic value by incorporating night BP, minimize biases and improve the diagnostic reproducibility of isolated clinic hypertension (ICH). We estimate the 24-h BP cut-off points that best discriminate and predict the two diagnostic thresholds of mean daytime BP for ICH (135/85 and 130/80 mmHg). Methods Cross-sectional, comparative, multicentre study in 6176 untreated hypertensive patients, whose BP was measured by ambulatory BP monitoring. ICH was defined with an office BP of >- 140/>- 90mmHg and a daytime BP of <135/<85mmHg (ICH1) or <130/80mmHg (ICH2). Sensitivity, specificity, positive likelihood ratio (LRR), odds ratio (OR), error rate, predictive values, k values and 95% confidence interval were calculated for each possible cut-off point for ICH1 and ICH2. Results One thousand eight hundred and seven patients (29.2%) and 960 patients (15.5%) met ICH1 and ICH2 criteria, respectively. The 24-h BP cut-off points that best predict ICH1 and ICH2 are less than 132/82mmHg (sensitivity: 93.6%, specificity: 94.3%, LRR: 16.6, OR: 1367.1, error rate: 5.9, k 0.86) and less than 127/77mmHg (sensitivity: 90.8%, specificity: 97.4%, LRR: 34.6, OR: 1041.5, error rate: 3.6,k 0.86), respectively. These values achieved the best balance of sensitivity and specificity, together with the highest values of LRR and OR and the lowest error rate. Conclusion The 24-h BP cut-off point that best predicts the daytime criterion of less than 135/85 and less than 130/80mmHg are 132/82 and 127/77mmHg, respectively. These 24-h cut-off points may add value to ambulatory blood pressure monitoring for both diagnostic and management future decisions. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.