Systematic review and a meta-analysis of hospital and surgeon volume/outcome relationships in colorectal cancer surgery

Background: Numerous hospitals worldwide are considering setting minimum volume standards for colorectal surgery. This study aims to examine the association between hospital and surgeon volume on outcomes for colorectal surgery. Methods: Two investigators independently reviewed six databases from inception to May 2016 for articles that reported outcomes according to hospital and/or surgeon volume. Eligible studies included those in which assessed the association hospital or surgeon volume with outcomes for the surgical treatment of colon and/or rectal cancer. Random effects models were used to pool the hazard ratios (HRs) for the association between hospital/surgeon volume with outcomes. Results: There were 47 articles pooled (1,122,303 patients, 9,877 hospitals and 9,649 surgeons). The metaanalysis demonstrated that there is a volume-outcome relationship that favours high volume facilities and high volume surgeons. Higher hospital and surgeon volume resulted in reduced 30-day mortality (HR: 0.83; 95% CI: 0.78-0.87, P< 0.001 & HR: 0.84; 95% CI: 0.80-0.89, P< 0.001 respectively) and intra-operative mortality (HR: 0.82; 95% CI: 0.76-0.86, P< 0.001 & HR: 0.50; 95% CI: 0.40-0.62, P< 0.001 respectively). Post-operative complication rates depended on hospital volume (HR: 0.89; 95% CI: 0.81-0.98, P< 0.05), but not surgeon volume except with respect to anastomotic leak (HR: 0.59; 95% CI: 0.37-0.94, P< 0.01). High volume surgeons are associated with greater 5-year survival and greater lymph node retrieval, whilst reducing recurrence rates, operative time, length of stay and cost. The best outcomes occur in high volume hospitals with high volume surgeons, followed by low volume hospitals with high volume surgeons. Conclusions: High volume by surgeon and high volume by hospital are associated with better outcomes for colorectal cancer surgery. However, this relationship is non-linear with no clear threshold of effect being identified and an apparent ceiling of effect.