Self-monitoring of BP for high-risk pregnancy not so useful: JAMA study

The COVID-19 pandemic has led to the frequent use of telemedicine and the common recommendation for self-monitoring of blood pressure (SMBP) during pregnancy for individuals at risk for or with hypertensive disorders of pregnancy, as an adjunct to or substitute for some aspects of in-person prenatal care visits.

Self Monitoring BP from 20 weeks' gestation until delivery or development of hypertension, in addition to usual care, did not lead to an earlier diagnosis of clinical hypertension, the results of the BUMP-1 trial has shown. The trial results have been published in the recent edition of JAMA.

In the Blood Pressure Monitoring in High Risk Pregnancy to Improve the Detection and Monitoring of Hypertension 1 that is (BUMP 1) trial, Tucker and colleagues investigated whether SMBP, in addition to usual prenatal care among individuals at increased risk for a hypertensive disorder of pregnancy, leads to earlier detection of hypertension.

Increased risk of hypertensive disorders of pregnancy was determined based on common risk factors of varying magnitude for preeclampsia, such as age, preeclampsia history, or chronic kidney disease. Individuals were recruited in the second trimester and self-monitored their BP 3 times a week until delivery with a monitor validated in pregnancy and entered their data into a mobile phone app. If blood pressures greater than 140/90 mm Hg were documented, the app automatically recommended participants call their maternity unit for further instructions. This app-based protocol was compared with usual care.

Primary outcome data were available for 2346 of 2441 randomized study participants. Baseline characteristics were similar for both groups. Among the 15% of individuals who developed a hypertensive disorder of pregnancy, time from randomization to diagnosis was not statistically significantly different that is 104 days in the SMBP group vs 106 days in the usual care group, The BUMP 1 trial raises several issues.

BUMP 1 enrolled a heterogeneous group of individuals at-risk for preeclampsia, based on vascular risk factors. Although subgroup analysis by recommended use of aspirin, socioeconomic status, or gestational age at study entry showed no differences, subgroup analyses by clinical indication for trial entry would have additional utility to clinicians.

Moreover, in clinical practice, the question extends to beyond latency in diagnosis of hypertensive disorders of pregnancy and includes the effect of the diagnosis on maternal and neonatal morbidity, particularly among the highest-risk individuals. BUMP 1 was not powered to identify differences in these outcomes.

The BUMP 1 trial also identified an important challenge in the management of hypertension in that 26.9% of participants had a discrepancy between home and clinic BP readings despite using a validated monitor.

These discrepancies, attributable to white coat hypertension and masked hypertension, may have also contributed to the negative primary outcome.

In addition, in the context of the COVID-19 pandemic, during which telemedicine and self-monitoring might replace usual care for low-risk individuals, the clinical benefit of SMBP remains untested.