Hospital variation in sphincter-preservation rates in rectal cancer treatment: results of a population-based study in the Netherlands

Background: This study aimed to examine the sphincter-preservation rate variations in rectal cancer surgery. The influence of hospital volume on sphincter-preservation rates and short-term outcomes (anastomotic leakage (AL), positive circumferential resection margin (CRM), 30- and 90-day mortality rates) were also analysed. Methods: Non-metastasized rectal cancer patients treated between 2009 and 2016 were selected from the Netherlands Cancer Registry. Surgical procedures were divided into sphincter-preserving surgery and an end colostomy group. Multivariable logistic regression models were generated to estimate the probability of undergoing sphincter-preserving surgery according to the hospital of surgery and tumour height (low, 5 cm or less, mid, more than 5 cm to 10 cm, and high, more than 10 cm). The influence of annual hospital volume (less than 20, 20-39, more than 40 resections) on sphincter-preservation rate and short-term outcomes was also examined. Results: A total of 20 959 patients were included (11 611 sphincter preservation and 8079 end colostomy) and the observed median sphincter-preservation rate in low, mid and high rectal cancer was 29.3, 75.6 and 87.9 per cent respectively. After case-mix adjustment, hospital of surgery was a significant factor for patients' likelihood for sphincter preservation in all three subgroups (P<0.001). In mid rectal cancer, borderline higher rates of sphincter preservation were associated with low-volume hospitals (odds ratio 1.20, 95 per cent c.i. 1.01 to 1.43). No significant association between annual hospital volume and sphincter-preservation rate in low and high rectal cancer nor short-term outcomes (AL, positive CRM rate and 30- and 90-day mortality rates) was identified. Conclusion: This population-based study showed a significant hospital variation in sphincter-preservation rates in rectal surgery. The annual hospital volume, however, was not associated with sphincter-preservation rates in low, and high rectal cancer nor with other short-term outcomes.