【文献名】
Myers MG et al.: Conventional versus automated measurement of blood pressure in primary care patients with systolic hypertension: randomized parallel design controlled trial.BMJ 2011; 342:d286.
【要約】
【Objective】
To compare the quality and accuracy of manual office blood pressure and automated office blood pressure using the awake ambulatory blood pressure as a gold standard.
【Design】
Multi-site cluster randomized controlled trial.
【Setting】
Primary care practices in five cities in eastern Canada.
【Participants】
555 patients with systolic hypertension and no serious comorbidities under the care of 88 primary care physicians in 67 practices in the community.
【Interventions】
Practices were randomly allocated to either ongoing use of manual office blood pressure (control group) or automated office blood pressure (intervention group) using the BpTRU device. The last routine manual office blood pressure (mm Hg) was obtained from each patient’s medical record before enrolment. Office blood pressure readings were compared before and after enrolment in the intervention and control groups; all readings were also compared with the awake ambulatory blood pressure.
【Main outcome measure】
Difference in systolic blood pressure between awake ambulatory blood pressure minus automated office blood pressure and awake ambulatory blood pressure minus manual office blood pressure.
【Results】
Cluster randomization allocated 31 practices (252 patients) to manual office blood pressure and 36 practices (303 patients) to automated office blood pressure measurement. The most recent routine manual office blood pressure (149.5 (SD 10.8)/81.4 (8.3)) was higher than automated office blood pressure (135.6 (17.3)/77.7 (10.9)) (P<0.001). In the control group, routine manual office blood pressure before enrolment (149.9 (10.7)/81.8 (8.5)) was reduced to 141.4 (14.6)/80.2 (9.5) after enrolment (P<0.001/P=0.01), but the reduction in the intervention group from manual office to automated office blood pressure was significantly greater (P<0.001/P=0.02). On the first study visit after enrolment, the estimated mean difference for the intervention group between the awake ambulatory systolic/diastolic blood pressure and automated office blood pressure (−2.3 (95% confidence interval −0.31 to −4.3)/−3.3 (−2.7 to −4.4)) was less (P=0.006/P=0.26) than the difference in the control group between the awake ambulatory blood pressure and the manual office blood pressure (−6.5 (−4.3 to −8.6)/−4.3 (−2.9 to −5.8)). Systolic/diastolic automated office blood pressure showed a stronger (P<0.001) within group correlation (r=0.34/r=0.56) with awake ambulatory blood pressure after enrolment compared with manual office blood pressure versus awake ambulatory blood pressure before enrolment (r=0.10/r= 0.40); the mean difference in r was 0.24 (0.12 to 0.36)/0.16 (0.07 to 0.25)). The between group correlation comparing diastolic automated office blood pressure and awake ambulatory blood pressure (r=0.56) was stronger (P<0.001) than that for manual office blood pressure versus awake ambulatory blood pressure (r=0.30); the mean difference in r was 0.26 (0.09 to 0.41). Digit preference with readings ending in zero was substantially reduced by use of automated office blood pressure.
【Conclusion】
In compliant, otherwise healthy, primary care patients with systolic hypertension, introduction of automated office blood pressure into routine primary care significantly reduced the white coat response compared with the ongoing use of manual office blood pressure measurement. The quality and accuracy of automated office blood pressure in relation to the awake ambulatory blood pressure was also significantly better when compared with manual office blood pressure.
【考察とディスカッション】
起床時の自由行動下血圧測定（ABPM; Ambulatory blood pressure monitor）をgold standard にした場合、外来診療において血圧は手動で測るよりも自動血圧計で測定する方が正確である、という結果であった。HCFMでは外来の血圧測定は看護師が自動血圧計で測定していることが多く、この研究結果が医師の行動の変化には結びつかないが、診察室で手動で血圧を測定する医師も多いため、参考になるのではないだろうか？
【開催日】
２０１１年２月２３日（水）