Can an automatic oscillometric device replace a mercury sphygmomanometer on blood pressure measurement? a systematic review and meta-analysis

Objective: A mercury sphygmomanometer has been considered a gold standard for measuring blood pressure. However, by the Minamata Convention on Mercury, the traditional mercury sphygmomanometer is being replaced by an automated oscillometric device. This study aimed to provide scientific evidence to determine whether an automated oscillometric device can replace a mercury sphygmomanometer and if it is applicable in routine practice. Methods: MEDLINE, EMBASE, the Cochrane Library, and CINAHL were searched on 4 May 2018. Studies comparing blood pressure measurements between automated oscillometric devices and mercury sphygmomanometers were included. Study characteristics were abstracted using the evidence table, and random-effects meta-analyses were conducted. Results: Data were compiled from 24 studies comprising 47 759 subjects. The results of meta-analysis showed that automated oscillometric devices measured lower than mercury sphygmomanometers for both systolic blood pressure (mean differences -1.75 mmHg, 95% confidence intervals: -3.05 to -0.45, I-2 = 91.0%) and diastolic blood pressure (mean differences -1.20 mmHg, 95% confidence intervals: -2.16 to -0.24, I-2 = 95.0%). In sub-group analyses by manufacturer, BpTRU measured lower than the mercury sphygmomanometer and OMRON showed no difference compared to the mercury sphygmomanometer for both systolic and diastolic blood pressure, but the results differed depending on the devices. Conclusion: As a result of this review, the difference in blood pressure between the mercury sphygmomanometer and the automated oscillometric device was within 5 mmHg, but the heterogeneity between the studies was very high. The automated oscillometric devices showed differences in blood pressure results according to the manufacturer and product type.