Title:
Diagnosing hypertension in primary care: the importance of night-time blood pressure assessment

MRCGP magazine Sept 2022

Background
Ambulatory blood pressure monitoring (ABPM) has become less frequent in primary care since the
COVID-19 pandemic, with home blood pressure monitoring (HBPM) often the preferred alternative;
however, HBPM cannot measure night-time blood pressure (BP) and patients whose night-time BP
does not dip or rises (reverse-dipping) have poorer cardiovascular outcomes.

Aim
To investigate the importance of measuring night-time BP when assessing individuals for
hypertension.

Retrospective cohort study of two patient populations; the first being hospital patients admitted to
four UK acute hospitals and the second being participants of the BP-Eth study recruited from 28 UK
GP practices.
Method
Using blood pressure data collected for the two cohorts, we studied three systolic blood pressure
(SBP) phenotypes (dipper, non-dipper and reverse-dipper).
Results
Among the hospital cohort (n=21,739) 48.9% patients were ‘reverse-dippers’, with an average daynight SBP difference of -8.0 mmHg. Among the community cohort (n=585) 10.8% patients were
‘reverse-dippers’ with an average day-night SBP difference of -8.5 mmHg. Non-dipper and reversedipper phenotypes both have lower day-time SBP and higher night-time SBP than the dipper
phenotype. Average day-time SBP was lowest in the reverse-dipping phenotype (6.5 mmHg and 6.8
mmHg lower than for the dipper phenotype in the hospital and community cohorts, respectively), thus
placing them at risk of undiagnosed, or masked hypertension.
Conclusion
Not measuring night-time BP puts all groups other than dippers at risk of failure to identify
hypertension. We recommend that GPs should offer ABPM to all patients aged ?60 as a minimum,
when assessing for hypertension.

G Mohan