Cluster-Randomized Controlled Trial of Oscillometric vs. Manual Sphygmomanometer for Blood Pressure Management in Primary Care (CRAB)
Nelson, MR and Quinn, S and Bowers-Ingram, L and Nelson, JM and Winzenberg, TM, Cluster-Randomized Controlled Trial of Oscillometric vs. Manual Sphygmomanometer for Blood Pressure Management in Primary Care (CRAB) , American Journal of Hypertension, 22, (6) pp. 598-603. ISSN 0895-7061 (2009) [Refereed Article]
Although mercury sphygmomanometers are seen as the gold standard instrument for blood pressure (BP) measurement, they are being withdrawn due to safety concerns. CRAB was a clusterrandomized controlled trial in 24 family practices in Tasmania, Australia, which aimed to determine the effect of an oscillometric
device on BP management.
Cluster-randomized controlled trial. Intervention practices were
supplied with automated monitors and control (usual care)
practices used mercury or aneroid sphygmomanometers. They were
subsequently audited by a research nurse. Usual care practice audit
periods were matched to intervention practices. All analyses were
intention-to-treat and adjusted for potential clustering. Differences
in BP were analyzed using generalized estimating equations.
All other outcomes were analyzed using multilevel mixed-effects
Poisson regression. Post hoc analyses were performed to determine
the mediators of changes in prescribing behavior.
A total of 3,355 records were reviewed (828 visits had BP
recordings). The percentage of BP recordings ending in "0" was
significantly lower in intervention vs. usual care practices (systolic
BP (SBP) 18% (107/587) vs. 71% (233/329), diastolic BP (DBP) 20%
(119/584) vs. 70% (229/328), P < 0.001). The mean of SBP recordings
in the intervention group was 7.5 mm Hg (95% confidence interval
(CI) 5.2, 9.9 mm Hg, P < 0.001) higher than in the usual care group.
Patients taking BP lowering drugs were more likely (incidence
rate ratio (IRR) 1.3, 95% CI 1.1, 1.7, P = 0.01) to have a BP lowering
drug prescribed if they were in the intervention compared to the
Although digit preference was largely eliminated by oscillometric
measurement, prescribing behavior was mediated by SBP.