title: Sensitivity and specificity in the diagnosis of hypertension with different methods.
abstract: OBJECTIVE
  To evaluate sensitivity and specificity of different protocols for blood pressure measurement for the diagnosis of hypertension in adults.
  
  
  METHODS
  Cross-sectional study conducted in a non-probabilistic sample of 250 public servants of both sexes aged 35 to 74 years in Vitória, southeastern Brazil, between 2008 and 2010. The participants had their blood pressure measured using three different methods: clinic measurement, self-measured and 24-hour ambulatory measurement. They were all interviewed to obtain sociodemographic information and had their anthropometric data (weight, height, waist circumference) collected. Clinic measurement and self-measured were analyzed against the gold standard ambulatory measurement. Measures of diagnostic performance (sensitivity, specificity, accuracy and positive and negative predictive values) were calculated. The Bland & Altman method was used to evaluate agreement between ambulatory measurement (standard deviation for daytime measurements) and self-measured (standard deviation of four measurements). A 5% significance level was used for all analyses.
  
  
  RESULTS
  Self-measured blood pressure showed higher sensitivity (S=84%, 95%CI 75;93) and overall accuracy (0.817, p<0.001) in the diagnosis of hypertension than clinic measurement (S=79%, 95%CI 73;86, and overall accuracy=0.815, p<0.001). Despite the strong correlation with daytime ambulatory measurement values (r=0.843, p<0.001), self-measured values did not show good agreement with daytime systolic ambulatory values (bias=5.82, 95%CI 4.49;7.15). Seven (2.8%) cases of white coat hypertension, 26 (10.4%) of masked hypertension and 46 (18.4%) of white-coat effect were identified.
  
  
  CONCLUSIONS
  The study shows that self-measured blood pressure has higher sensitivity than clinic measurement to identify true hypertension. The negative predictive values found confirm the superiority of self-measured when compared to clinic in identifying truly normotensive individuals. However, clinic measurement cannot be replaced with self-measured, as it is still the most reliable method for the diagnosis of hypertension.
authors.affiliation: Secretaria Municipal de Saúde, Vitória, ES, Brasil.
authors.forename: Larissa Rangel
authors.initials: LR
authors.lastname: Nascimento
authors.forename: Anna Paula
authors.initials: AP
authors.lastname: Coelli
authors.forename: Nágela Valadão
authors.initials: NV
authors.lastname: Cade
authors.forename: José Geraldo
authors.initials: JG
authors.lastname: Mill
authors.forename: Maria Del Carmen Bisi
authors.initials: Mdel C
authors.lastname: Molina
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry; D001795:Blood Pressure Determination / Q000379:methods*; D018660:Blood Pressure Monitoring, Ambulatory; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012648:Self Care / Q000379:methods; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013997:Time Factors