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EXPLORING CONTRIBUTORS TO TREATMENT VARIATION AMONG MEDICARE BENEFICIARY GASTRIC CANCER PATIENTS: A SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS (SEER)-MEDICARE DATABASE ANALYSIS
Mats Teeken
*, George Molina, Maite Liem, Mengyuan Ruan, Yu-Jen Chen
Surgical Oncology, Brigham and Women's Hospital, Boston, MA
INTRODUCTION
A curative-intent surgical resection should be the goal for all patients with locally and regionally advanced gastric cancer. The aim of this study was to evaluate the variation in delivery of curative-intent surgical care for potentially curable gastric cancer patients. We hypothesized that disparities in receiving treatment are due to unexplained factors rather than regional- or patient-level factors.
METHODS
Potentially curable stage I-III gastric cancer patients were identified using the 2010-2018 SEER-Medicare database. Treatment was defined as any form of gastrectomy within 1-year post-diagnosis. Treatment rates were calculated for the whole cohort and on the level of Health Service Areas (HSA), presented on a geospatial heatmap. The association between receiving treatment and patient-level factors (e.g. age, comorbidities, stage, race-ethnicity, socio-economic status) was examined with logistic regression models. Using hierarchical multivariable models, the proportion attributed to the total variability in receiving treatment was calculated for 4 components: patient factors, region (HSA), randomness, and unexplained factors. Because of reliability concerns, HSAs with <10 patients were excluded from treatment rate analysis, and HSAs with <30 patients were excluded from the components analysis.
RESULTS
A total of 4,640 patients met the inclusion criteria. Median age was 77 years old, 36% were female. The overall resection rate was 59.3% (2732/4604). Among the 40.6% (1872/4604) patients who did not receive surgical treatment, at the time of 1-year post-diagnosis, 45.4% (850/1872) patients had died due to their cancer and 43.3% (811/1872) were still alive. In univariable models, patient factors most strongly associated with failure to receive surgical treatment were age > 85 years (OR 0.27, p<0.01), >2 comorbidities (OR 0.59, p<0.01), rural residence (OR 0.71, p=0.02), and White ethnicity/race (OR 0.43, p<0.01, compared to Asian ethnicity/race). In the multivariable logistic regression models these associations remained significant, including the odds of receiving treatment for rural patients versus metro patients (OR=0.66, p=0.01). The treatment rate variability for 88 HSAs ranged from <30% for 1 HSA to more than 80% for some HSAs. Components analysis including 34 eligible HSAs showed that unexplained factors had the largest attribution (41.4%) to the total variance in treatment delivery.
CONCLUSION
These results might indicate poor access to surgical care for potentially curable gastric cancer among Medicare beneficiaries, especially rural patients. Unexplained factors were the largest contributor to variability in receiving curative-intent surgical treatment. Further research is needed to identify and evaluate these unexplained factors.
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