- Design
- Single-centre retrospective fuzzy regression discontinuity analysis
- Population
- 7,270 patients aged 60–89 having elective non-cardiac surgery
- Primary outcome
- Duration of intraoperative MAP <65 mmHg
- Effect
- −24.8 min (95% CI −71.1 to 21.5)
A Japanese hospital performs preoperative transthoracic echocardiography on every patient aged 75 or over. This retrospective study used that policy as a natural experiment — a regression discontinuity design — in 7,270 patients aged 60 to 89 having elective non-cardiac surgery, after excluding anyone with a guideline indication for echo.
At the age cutoff, the probability of having an echo rose by 43 percentage points. The estimated effect on intraoperative hypotension was a 25-minute reduction, but with an interval from 71 minutes less to 22 minutes more. Mortality, kidney injury, unplanned critical care admission and length of stay all had point estimates favouring echo, but every interval included no effect.
The design reduces the confounding that plagues observational studies of preoperative testing, but the result is imprecise: it neither shows benefit nor rules it out. It supports the existing guideline position that echo should be indicated by clinical findings rather than age alone.
- Order preoperative echo for clinical indications, not on age alone.
- Review murmur, breathlessness, heart failure signs and functional capacity before deciding on echo.
- Do not delay surgery for a routine echo in an older patient without an indication.
- Note the estimates were imprecise; benefit in some subgroups cannot be excluded.
Why it matters
It tests an age-based policy many hospitals use, with a design that limits the usual bias.
Don't overread it
The estimates were imprecise; this does not show echo is useless, only that age alone did not show clear benefit.
The statistics, in plain English
A regression discontinuity compares people just either side of a cutoff, who are otherwise similar, so differences can be attributed to the test. Here every outcome interval crossed zero, which means the study cannot tell benefit from no effect.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for anaesthesiology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free