In older adults with a prior fall history, orthostatic hypotension measured 30 seconds after standing is more strongly associated with fall risk within 12 months than orthostatic hypotension measured at 3 minutes, as the 30-second measurement retained statistical significance across all adjusted models while the 3-minute measurement did not.

When a person stands up quickly, blood pools in the legs and the heart cannot pump enough blood to the brain fast enough. The body's blood pressure sensors detect this drop and try to speed up the heart and tighten blood vessels, but in older adults who have fallen before, this response is too slow. The brain gets less blood for the first 30 seconds, which increases the chance of dizziness or fainting and leads to a fall. By 3 minutes, the body has had time to adjust, so the blood pressure reading no longer shows the dangerous early drop.