title: ESCAPE-ancillary blood pressure measurement study: end-digit preference in blood pressure measurement within a cluster-randomized trial.
abstract: BACKGROUND
  In a cluster-randomized trial including 1832 hypertensive patients, all 126 general practitioners (GPs) in the intervention group (IG) used an oscillometric device that was provided for blood pressure (BP) measurements. Of the 131 GPs of the control group (CG), 24.6% used an oscillometric device (OCG), and 75.4% used a manual device (MCG). At baseline, patients in the IG and CG were comparable for all clinical and biological characteristics, except BP, which was higher in the IG (146/84 vs. 139/81 mmHg; P<0.001). The purpose of this ancillary study was to assess whether these differences in BP values were related to the end-digit preference (EDP), selection bias, or both.
  
  
  METHODS
  Analysis was carried out and comparison was made of 3629 BP measurements by 257 GPs. Statistical analysis used hierarchical mixed-effect models with random physician effect and fixed-effect covariables.
  
  
  RESULTS
  The frequencies of 0 end digit were 16.7% in the IG, 32.4% in the OCG and 68.8% in the MCG for systolic BP (SBP; P<0.001 for all comparisons), and respectively 17.7, 38.1, and 74.1% for diastolic BP (DBP; P=0.017 for all comparisons). SBP was higher in the IG than in OCG (+3.65 mmHg, P=0.017). The same trend was observed for DBP, though not significant (+1.50 mmHg, P=0.20). The EDP in the CG led to a mean underevaluation of 2.4 mmHg (P<0.0005) of SBP and DBP.
  
  
  CONCLUSIONS
  The observed differences in BP between the groups are partly explained by the impact of EDP. Compared with the manual, oscillometric measurement may reduce EDP.
authors.affiliation: Department of General Practice, Tours Medical University, France. jean-pierre.lebeau@univ-tours.fr
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lebeau
authors.forename: Denis
authors.initials: D
authors.lastname: Pouchain
authors.forename: Dominique
authors.initials: D
authors.lastname: Huas
authors.forename: Franck
authors.initials: F
authors.lastname: Wilmart
authors.forename: Clarisse
authors.initials: C
authors.lastname: Dibao-Dina
authors.forename: Florent
authors.initials: F
authors.lastname: Boutitie
mesh_terms: D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000295:instrumentation*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000295:instrumentation*