Institution-level framework to estimate the impact of BMI on operative decision-making in patients undergoing colorectal surgery in a provincial cohort.

BACKGROUND

In colorectal surgery, a higher body mass index (BMI) is associated with increased technical difficulty, reduced use of minimally invasive surgery (MIS), and higher rates of conversion to open. While these associations are well established, less is known about how they vary across systems and providers. The study presents a methodological framework that evaluates the impact of obesity on operative approach and conversion risk in colorectal surgery and compares these associations between a provincial Canadian cohort (Nova Scotia (NS)) and National-Surgical-Quality-Improvement-Program (NSQIP), accounting for procedure-, surgeon-, and hospital-level variations.

METHODS

A retrospective cohort analysis was performed using NS (n = 3373) and NSQIP (n = 243,221) data between 2018 and 2022. Adult patients undergoing elective colectomy or proctectomy were included. Operative approach (open vs. laparoscopic) and conversion to open were the primary and secondary outcomes, respectively, and were compared between cohorts across BMI categories. Multivariate logistic regression identified independent predictors of conversion, with further stratification by procedure, surgeon, and hospital. Data analysis was performed using RStudio.

RESULTS

Laparoscopic utilization was lower in NS than NSQIP (36.4% vs. 49.3%, p < 0.0001), while conversion rates were higher (23.1% vs. 19.3%, p = 0.02). BMI was a significant independent predictor of conversion in both cohorts (NS 2.54, CI 1.23-5.50; NSQIP 1.61, CI 1.27-2.03), with a stronger effect in NS. A clear volume-outcome relationship emerged of surgeons with higher laparoscopic utilization had lower conversion rates, particularly in right hemicolectomies and anterior resections. Institutional factors were not independently associated with conversion.

CONCLUSION

Obesity markedly increases the risk of conversion in minimally invasive colorectal surgery, with greater impact in NS compared to NSQIP. Surgeon-level variation, rather than hospital factors, primarily drives differences in conversion. This study presents foundational evidence for perioperative decision-making and offers an opportunity for incorporating remote proctoring by higher-volume laparoscopic providers.