BACKGROUND AND PURPOSE:

• The effectiveness of self-monitoring blood pressure (SMBP) during pregnancy is not well-established
• Chappell et al. (JAMA, 2022) evaluated the effect of SMBP on blood pressure control and related outcomes among pregnant women with hypertension

METHODS:

• Unblinded, randomized clinical trial
  • Blood Pressure Monitoring in High Risk Pregnancy to Improve the Detection and Monitoring of Hypertension 2 (BUMP 2) trial
• Participants
  • Chronic hypertension (enrolled up to 37 weeks) or
  • Gestational hypertension (enrolled between 20 to 37 weeks)
• Interventions
  • SMBP using a validated monitor and a secure telemonitoring system in addition to usual care
  • Usual care alone: Blood pressure measured by health care professionals at regular antenatal clinics
• Sample size
  • Estimated 256 per group to detect a 5 mm Hg difference in systolic BP
  • 90% power and 5% level of significance (2-sided), accounting for 15% attrition
  • Sample size total increased to 600 to retain power in the cohorts of individuals with chronic and gestational hypertension
• Primary outcome
  • Difference in mean systolic blood pressure recorded by health care professionals between randomization and birth

RESULTS:

• Chronic hypertension: 444 participants (primary outcome data available)
  • Mean age: 36 years | mean gestation at entry: 20 weeks
• Gestational hypertension: 377 participants (primary outcome data available)
  • Mean age 34 years | mean gestation at entry: 33 weeks
• Mean systolic blood pressure: There was no statistically significant difference in either cohort
  • Chronic hypertension
    • SMBP: 133.8 mm Hg
    • Usual care: 133.6 mm Hg
    • Adjusted mean difference 0.03 mm Hg (95% CI, −1.73 to 1.79)
  • Gestational hypertension
    • SMBP: 137.6 mm Hg
    • Usual care: 137.2 mm Hg
    • Adjusted mean difference −0.03 mm Hg (95% CI, −2.29 to 2.24)
• Serious adverse events: There was no statistically significant difference in either cohort
  • Chronic hypertension
    • SMBP: 4
    • Usual care: 2
  • Gestational hypertension
    • SMBP: 4
    • Usual care: 1
• ‘White coat effect’
  • Approximately 25% of participants recorded only normal BP at home but had elevated clinic pressures
  • However, there was no difference in medications between SMBP and clinic monitoring, suggesting patients were treated based on clinic and not SMBP information

CONCLUSION:

• For individuals with hypertension during pregnancy, self-monitoring blood pressure did not improve blood-pressure control compared with usual care
• The authors state

The strengths of this trial included the intervention being developed iteratively with the input of pregnant individuals and behavioral change experts

It was appropriately powered including separately for chronic and gestational hypertension, undertaken in multiple maternity units across England with diverse sociodemographic characteristics (including a substantial proportion from non-White racial and ethnic groups), with recruitment completed prior to the COVID-19 pandemic

The results may, therefore, be generalizable to populations beyond those in the study

Learn More – Primary Sources:

Effect of Self-monitoring of Blood Pressure on Blood Pressure Control in Pregnant Individuals With Chronic or Gestational Hypertension: The BUMP 2 Randomized Clinical Trial

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