- Design
- Single-centre fuzzy regression discontinuity analysis
- Population
- 7,270 adults aged 60–89 having elective non-cardiac surgery without guideline echo indications
- Primary outcome
- Duration of intraoperative MAP below 65 mmHg
- Effect
- −24.8 minutes (95% CI −71.1 to 21.5); secondary outcomes imprecise
One Japanese centre had a policy of routine preoperative transthoracic echocardiography for everyone aged 75 or over. Researchers used that age cut-off in a regression discontinuity design — comparing patients just either side of 75 — to estimate the effect of the scan in 7,270 patients aged 60 to 89 having elective non-cardiac surgery, after excluding anyone with a guideline indication for echo.
The policy raised echo use by 43 percentage points at 75. The estimated effect on intraoperative hypotension was a 24.8-minute reduction, but with a very wide interval (−71.1 to 21.5). Point estimates for mortality, kidney injury, unplanned critical care admission and length of stay all leaned towards benefit, but none was precise enough to exclude no effect or harm.
This design is better at avoiding confounding than a standard cohort, but its answer is honest uncertainty. Age alone does not justify a scan; a murmur, breathlessness, heart failure signs or poor functional capacity still do.
- Order preoperative echo for a clinical indication, not on age alone.
- Indications include an unexplained murmur, suspected heart failure, unexplained breathlessness or known valve disease without recent imaging.
- Assess functional capacity at the bedside before deciding on further tests.
- Where echo capacity is limited, prioritise patients with symptoms or signs.
Why it matters
Age-based imaging rules use scarce capacity without clear evidence that they change outcomes.
Don't overread it
The estimates were imprecise — this does not show that echo is useless, only that age alone did not show a clear benefit.
The statistics, in plain English
A regression discontinuity compares patients just below and just above an age cut-off, who are otherwise very similar. The hypotension interval (−71 to +22 minutes) crosses zero widely, so the study cannot tell benefit from no effect. The result applies best to patients near 75.
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