Robotic gastrectomy in obesity: no advantage established

Design

systematic review and meta-analysis of 16 non-randomised comparative studies, ROBINS-I and GRADE, certainty very low

Population

overweight, obese or high-visceral-adiposity patients undergoing gastrectomy for gastric cancer; East Asian cohorts only

Primary outcome

overall and major postoperative complications, operative time, estimated blood loss

Effect

overall complications RR 0.81 (95% CI 0.60-1.10, I² 0%); major RR 0.56 (0.20-1.52); operative time +31.1 min (-9.6 to +71.9)

Sixteen comparative studies, all from South Korea, China or Japan, were pooled to ask whether the robot helps in the population where minimally invasive gastrectomy is hardest — patients who are overweight, obese, or have high visceral adiposity on computed tomography. Risk of bias was assessed with ROBINS-I and certainty with GRADE, with overlapping cohorts resolved outcome by outcome.

Nothing separated. Overall postoperative complications gave RR 0.81 (95% CI 0.60-1.10) across 10 studies and 1,695 participants, with no heterogeneity. Major complications gave RR 0.56 (0.20-1.52). Operative time favoured laparoscopy numerically by about 31 minutes (95% CI -9.6 to +71.9) but with I-squared of 92%, and blood loss differed by about 10 mL (-38.2 to +17.6). Certainty was very low for all four primary outcomes.

The reviewers are explicit that applicability to non-East-Asian patients is uncertain, and that matters here more than usual: visceral adiposity at a given body mass index differs between populations, and the adiposity thresholds used were not standardised across the included studies. Indian patients accumulate visceral fat at lower body mass index than East Asian cohorts on average, so neither the exposure definition nor the result transfers cleanly.

The honest reading is that the hypothesis is untested rather than refuted. What this does remove is the argument that high body mass index is on its own a reason to choose the robot for gastrectomy.

• Do not use raised body mass index alone as the justification for robotic rather than laparoscopic gastrectomy
• Where visceral adiposity is the concern, assess it on the preoperative staging computed tomography rather than inferring it from body mass index
• Counsel on operative time honestly: the direction favoured laparoscopy but the estimate was too heterogeneous to quote
• Expect no difference in blood loss between approaches on this evidence
• Treat these estimates as East Asian data when applying them to Indian patients, whose adiposity distribution differs

Why it matters

The difficult-anatomy argument is the main clinical case for robotic gastrectomy, and it has now been looked for and not found.

Don't overread it

Failing to find a difference in very-low-certainty non-randomised data is not the same as showing there is none.

The statistics, in plain English

Every interval here crosses the line of no difference, so no outcome was established either way. I-squared of 0% for overall complications means the studies agreed closely on that null — a more informative null than the operative time estimate, where I-squared of 92% means the studies disagreed so much that the pooled figure describes none of them. Very low GRADE certainty reflects that all 16 studies were non-randomised, so unmeasured differences between patients chosen for each approach could account for what was seen.

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