Timing important for assessing orthostatic hypotension, study finds

By Jane Lewis
Contrary to prevailing recommendations that orthostatic hypotension (OH) assessments be taken three minutes after rising, OH should be measured within one minute of standing, new research in JAMA Internal Medicine suggests. 

Commenting on this research, Dr Susan Corcoran, cardiologist at Alfred Hospital and Baker Heart and Diabetes Institute in Melbourne, said the study adds to the growing body of literature linking OH to adverse outcomes, including all-cause mortality, coronary heart disease, heart failure and stroke. 

‘In addition to raising awareness of the importance of this condition, it allows us to reflect on the physiology of OH and how it is assessed clinically,’ she told Medicine Today

The US study was conducted in a cohort of 11,429 adults aged 44 to 66 years (mean age 54 years; 54% women), in whom OH (defined as a drop in blood pressure [systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg] from the supine to standing position) was measured up to five times at 25-second intervals. The researchers determined the association of each of the five OH measurements with history of dizziness on standing and risk of falls, fracture, syncope, motor vehicle crashes and all-cause mortality during a median of 23 years’ follow up. 

Compared with OH assessed after one minute of standing, OH detected within one minute was associated with greater risk of falls, fracture, syncope, motor vehicle crashes and mortality. In addition, OH assessed at the first measurement (mean time 28 seconds) was the only measurement associated with higher odds of dizziness (odds ratio, 1.49). 

‘Our study demonstrates that early assessments of OH (within one minute) may be not only time-saving but also most clinically relevant and highly informative for long-term prognosis,’ the authors concluded. 

The authors of a commentary accompanying the study agreed with the researchers’ conclusions, but pointed out that ‘there is an important subgroup of patients with orthostatic symptoms associated with a significant orthostatic decline in BP that does not develop until after three minutes of standing (delayed OH).’ Therefore, rather than abandoning the three-minute orthostatic BP measurement, they advocated obtaining both one- and three-minute orthostatic BP measurements. 

‘When assessing orthostatic dizziness, multiple measurements taken from the earliest possible time after standing and continued frequently for up to three minutes, or longer if the clinical history is suggestive, can help correlate blood pressure changes with symptoms,’ advised Dr Corcoran. These measurements may also guide management, which may include a review of medications and advice regarding simple measures such as staying hydrated, changing posture more slowly and using leg-tensing manoeuvres, she added. 

‘The initial reaction to diagnosing OH can be to withdraw antihypertensives, but there is evidence that good hypertension control can reduce adverse outcomes in the hypertensive elderly with OH.’ Monitoring BP over a 24-hour period to assess the diurnal pattern, followed by gradual up-titration of antihypertensives (which may be moved to night time if supine nocturnal hypertension is present) is the general recommendation, she noted.
JAMA Intern Med 2017; doi: 10.1001/jamainternmed.2017.2937.
JAMA Intern Med 2017; doi: 10.1001/jamainternmed.2017.2923.