Risk-adjusted pathologic margin positivity rate as a quality indicator in rectal cancer surgery

Abstract

Purpose: Margin positivity after rectal cancer resection is associated with poorer outcomes. We previously developed an instrument for calculating hospital risk-adjusted margin positivity rate (RAMP) that allows identification of performance-based outliers and may represent a rectal cancer surgery quality metric.

Methods: This was an observational cohort study of patients with rectal cancer within the National Cancer Data Base (2003 to 2005). Hospital performance was categorized as low outlier (better than expected), high outlier (worse than expected), or non-RAMP outlier using standard observed-to-expected methodology. The association between outlier status and overall risk of death at 5 years was evaluated using Cox shared frailty modeling.

Results: Among 32,354 patients with cancer (mean age, 63.8 +/-13.2 years; 56.7% male; 87.3% white) treated at 1,349 hospitals (4.9% high outlier, 0.7% low outlier), 5.6% of patients were treated at high outliers and 3.0% were treated at low outliers. Various structural (academic status and volume), process (pathologic nodal evaluation and neoadjuvant radiation therapy use), and outcome (sphincter preservation, readmission, and 30-day postoperative mortality) measures were significantly associated with outlier status. Five-year overall survival was better at low outliers (79.9%) compared with high outliers (64.9%) and nonoutliers (68.9%; log-rank test, P < .001). Risk of death was lower at low outliers compared with high outliers (hazard ratio [HR], 0.61; 95% CI, 0.50 to 0.75) and nonoutliers (HR, 0.69; 95% CI, 0.57 to 0.83). Risk of death was higher at high outliers compared with nonoutliers (HR, 1.12; 95% CI, 1.03 to 1.23).

Conclusion: Hospital RAMP outlier status is a rectal cancer surgery composite metric that reliably captures hospital quality across all levels of care and could be integrated into existing quality improvement initiatives for hospital performance.

Fig 1.

Flow diagram of study design. AJCC, American Joint Committee on Cancer.

Fig 2.

Association between hospital risk-adjusted margin positivity rate outlier status and (A) facility type (trend test, P < .001); (B) hospital surgical volume (trend test, P < .001); (C) number of lymph nodes pathologically evaluated (P < .001); (D) use and timing of radiation therapy (trend test, P < .001); (E) performance of a sphincter-preserving procedure (patients with rectosigmoid tumors excluded; trend test, P = .02); (F) 30-day postoperative readmission (trend test, P = .01); and (G) 30-day postoperative mortality (trend test, P = .007).

Fig 3.

Unadjusted overall survival rates by risk-adjusted margin positivity rate hospital outlier status among (A) the entire cohort and (B) patients with non-T4 tumors. Log-rank P < .001 for both.