Volume-outcome relationship in intra-abdominal robotic-assisted surgery: a systematic review

As robotic-assisted surgery (RAS) expands to smaller centres, platforms are shared between specialities. Healthcare providers must consider case volume and mix required to maintain quality and cost-effectiveness. This can be informed, in-part, by the volume-outcome relationship. We perform a systematic review to describe the volume-outcome relationship in intra-abdominal robotic-assisted surgery to report on suggested minimum volumes standards. A literature search of Medline, NICE Evidence Search, Health Technology Assessment Database and Cochrane Library using the terms: "robot*", "surgery", "volume" and "outcome" was performed. The included procedures were gynecological: hysterectomy, urological: partial and radical nephrectomy, cystectomy, prostatectomy, and general surgical: colectomy, esophagectomy. Hospital and surgeon volume measures and all reported outcomes were analysed. 41 studies, including 983,149 procedures, met the inclusion criteria. Study quality was assessed using the Newcastle-Ottawa Quality Assessment Scale and the retrieved data was synthesised in a narrative review. Significant volume-outcome relationships were described in relation to key outcome measures, including operative time, complications, positive margins, lymph node yield and cost. Annual surgeon and hospital volume thresholds were described. We concluded that in centres with an annual volume of fewer than 10 cases of a given procedure, having multiple surgeons performing these procedures led to worse outcomes and, therefore, opportunities should be sought to perform other complimentary robotic procedures or undertake joint cases.