Included studies had to be randomised controlled trials (RCTs) that compared an intervention with placebo and measured postural drop as an outcome (defined as a sustained reduction of systolic blood pressure of at least 20mmHg or diastolic blood pressure of 10mmHg within three min of standing or head-up tilt to at least 60° on a tilt table). The primary outcome measures of interest were changes in orthostatic symptoms, change in office blood pressure (lying and standing/tilted systolic and diastolic blood pressure, and postural drop).
Trials that involved astronauts, healthy volunteers or measured post-prandial hypotension or neurally mediated hypotension (vasovagal syncope) as opposed to orthostatic hypotension were excluded.
The interventions were fluid, hydration, water; salt, sodium chloride oxilofrine, potassium chloride; bed tilt, elevating bed; counter manoeuvres/manoeuvers; compression stocking/hose/bandage/garment, abdominal compression; antihypertensives; fludrocortisone; erythropoietin; sympathomimetics (midodrine, dihydroxyphenylserine, yohimbine, ephedrine, pseudoephedrine, dihydroergotamine); acetyl cholinesterase inhibition, pyridostigmine; selective serotonin reuptake inhibitors; serotonin-norepinephrine reuptake inhibitors; vasopressin analogues; methylphenidate; dextroamphetamine; caffeine; dopamine receptor antagonist (metoclopramide, domperidone); and indomethacin.
In a third of included trials, patients had a mean or median age of older than 65 years; in a few trials, patients had a mean or median age older than 75 years. Eleven different populations were identified throughout the included studies, with a few studies inadequately characterising the underlying cause of orthostatic hypotension. Over a third of the trials included a varied mix of patients, rather than concentrating on one specific disease process.
The number of reviewers assessing study eligibility was not stated.