Sutureless off-clamp partial nephrectomy met its noninferiority margin — with a fistula signal to watch

Design

Single-centre, single-surgeon randomised controlled noninferiority trial with covariate-adaptive 1:1 allocation

Population

248 patients with cT1-2N0M0 renal tumours undergoing purely off-clamp robotic partial nephrectomy

Primary outcome

Trifecta achievement at discharge, prespecified noninferiority margin −10%

Effect

93% sutureless vs 95% renorrhaphy; absolute difference −2.4% (90% CI −7.4 to 2.6), one-sided p = 0.006

Two hundred and forty-eight patients with cT1-2N0M0 renal tumours were randomised, in a single-centre single-surgeon trial with covariate-adaptive allocation balancing age, sex, baseline renal function and tumour complexity, to sutureless or renorrhaphy after purely off-clamp robotic partial nephrectomy. The primary endpoint was Trifecta at discharge, tested against a prespecified noninferiority margin of −10%. Trifecta was reached in 93% of the sutureless arm and 95% of the renorrhaphy arm, absolute difference −2.4% (90% CI −7.4 to 2.6), one-sided p = 0.006. Transfusion occurred in 2.4% against 0%, acute kidney injury in 1.6% of both. Renal function was stable to 12 months and one-year recurrence-free survival was 99% in both arms.

The rationale for omitting the renorrhaphy is that the sutures themselves devascularise parenchyma, so the reconstruction meant to secure the kidney is part of what damages it. This trial does not demonstrate a functional advantage — renal function was stable in both arms — it demonstrates that omitting the step does not cost surgical quality within a 10% margin.

The number that deserves attention is nine urinary fistulae overall, all managed with temporary stenting, at a higher rate in the sutureless group with p = 0.08. A non-significant p-value in a trial powered for a different endpoint is not reassurance; it is an unresolved question about the complication the technique would be expected to cause. Combine that with a single surgeon, a single centre and 12 months of oncological follow-up, and the honest statement is that this is feasible in expert hands for selected tumours, not that it is ready to become the default. Anyone adopting it should audit their own fistula and stenting rate deliberately, because a trial of this size could not have detected a meaningful excess.

• Restrict this to selected cT1-2 tumours and to surgeons already performing purely off-clamp resection.
• Audit urinary fistula and stenting rates prospectively if you adopt it — that is the signal the trial could not resolve.
• Do not present it to a patient as better for renal function; function was stable in both arms.
• Noninferiority was tested at a 10% margin, which is wide — a real 5% difference would have passed.
• Oncological follow-up is 12 months; nothing here speaks to five-year outcomes.

The statistics, in plain English

A noninferiority trial asks whether the new approach is no worse than the old by more than a prespecified amount, and here that amount was 10 percentage points of Trifecta. The observed difference, −2.4% with a 90% confidence interval reaching −7.4%, sits inside that margin — so the conclusion is that sutureless is not more than 10% worse, which is a weaker claim than 'as good as'. The one-sided p of 0.006 refers to the margin test, not to a difference between arms. Meanwhile the fistula comparison at p = 0.08 is the mirror image: with nine events in 248 patients there is no power to detect anything but a large excess, so a non-significant result here carries almost no information.

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