Risk-Adjusted Margin Positivity Rate as a Surgical Quality Metric for Non-Small Cell Lung Cancer

Abstract

Background: Incomplete lung cancer resection connotes poor prognosis; the incidence varies with patient demographic, clinical, and institutional factors. We sought to develop a valid, survival impactful, facility-based surgical quality metric that adjusts for related patient demographic and clinical characteristics.

Methods: Facilities performing resections for patients diagnosed with stage I to IIIA non-small cell lung cancer in the National Cancer Data Base between 2004 and 2011 were identified. Multivariate logistic regression modeling was used to estimate the expected number of margin-positive cases by adjusting for patient risk mix and calculate the observed-to-expected ratio for each facility. Facilities were categorized as outperformers (observed-to-expected ratio less than 1, p < 0.05), nonoutliers (p > 0.05), and underperformers (observed-to-expected ratio greater than 1, p < 0.05); and their characteristics across performance categories were compared by χ² tests. Multivariate Cox proportional hazard analyses were conducted, adjusting for patient demographic and clinical characteristics.

Results: A total of 96,324 patients underwent surgery at 809 facilities. The overall observed margin-positive rate was 4.4%. Sixty-one facilities (8%) were outperformers, 644 (80%) were nonoutliers, and 104 (13%) were underperformers. One third (36%) of National Cancer Institute-designated facilities, 13% of academic comprehensive cancer programs, 5% of comprehensive community cancer programs, and 13% of "other" facilities achieved outperforming status but no community cancer programs did. Interestingly, 9% of National Cancer Institute-designated facilities and 11% of academic comprehensive cancer program facilities were underperformers. Adjusting for patient demographic and clinical characteristics, outperformers had a 5-year all-cause hazard ratio of 0.88 (95% confidence interval: 0.85 to 0.91, p < 0.0001) compared with nonoutliers, and 0.80 (95% confidence interval: 0.77 to 0.84, p < 0.0001) compared with underperformers.

Conclusions: Facility performance in lung cancer surgery can be captured by the risk-adjusted margin-positivity rate, potentially providing a valid quality improvement metric.

Figure 1

Patient selection schema. *Non-small cell histology was identified through International Classification of Diseases for Oncology, 3^rd version (ICD-O-3) histology codes: 8010-8040, 8050-8076, 8140, 8143, 8211, 8230-8231, 8246, 8250-8260, 8310, 8320, 8323, 8430, 8470-8490, 8550-8573, 8980, 8981. †Cancer-directed surgery was identified through site-specific surgical codes (21, 22, 30 –80), including sub-lobectomy, lobectomy, bi-lobectomy, and pneumonectomy.

Figure 2

Margin-positive rate by stage.

Figure 3

Kaplan-Meier survival curves by facility performance category.