The 48-hour rule may not apply to periprosthetic hip fractures

Design

Target trial emulation (clone-censor-weight) of a hospital administrative database

Population

4,564 patients with periprosthetic hip fracture (mean age 84, 80% female)

Primary outcome

30- and 90-day mortality, early vs delayed surgery

Effect

30-day 1.72% vs 0.83% (risk ratio 2.06, 0.64–3.73); 90-day 2.35% vs 2.31% (1.01, 0.59–1.68)

Early surgery is the standard for native hip fractures, and it is tempting to apply the same 48-hour target to periprosthetic hip fractures. This study tested that using target trial emulation, a method that removes the immortal-time bias that made delayed surgery look falsely safe in earlier observational work.

Across 4,564 patients (mean age 84), early surgery within two days showed no clear short-term mortality advantage over delayed surgery at 3–10 days: 30-day mortality 1.72% versus 0.83% and 90-day mortality 2.35% versus 2.31%, both with confidence intervals spanning no difference. A conventional analysis, vulnerable to immortal time, understated mortality in the delayed group — illustrating the bias.

The practice point is nuanced, not a licence to delay. For a periprosthetic hip fracture — often complex, in an elderly, comorbid patient — the evidence does not support rushing to operate within 48 hours purely to cut mortality, so taking the time needed for medical stabilisation and operative planning is defensible. Avoidable delay is still not justified, and complications and function were not assessed here.

• With immortal-time bias removed, early surgery (within 2 days) showed no short-term mortality benefit over delayed (3–10 days).
• 30-day mortality 1.72% vs 0.83% (risk ratio 2.06, 95% CI 0.64–3.73); 90-day 2.35% vs 2.31% (risk ratio 1.01, 0.59–1.68).
• A conventional timing analysis understated delayed-group mortality — the immortal-time trap.
• Take the time needed for stabilisation and planning in periprosthetic hip fracture, but do not permit avoidable delay.

Why it matters

It challenges the reflex to extend the native-hip 48-hour rule to a different, more complex fracture without evidence.

Don't overread it

This was an observational emulation of mortality only — it does not address complications, reoperation or function, and does not justify avoidable delay.

The statistics, in plain English

Both mortality comparisons had confidence intervals crossing no difference, so neither strategy was shown to save lives short-term. The value of the study is methodological: target trial emulation prevents the delayed group from looking artificially safe because patients had to survive to reach delayed surgery.

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