Estimating hospitals’ all-payer volume of cancer surgeries from Fee-for-Service Medicare claims

Background: Despite prior research establishing a relationship between volume and outcomes in certain surgical procedures for cancer, there is still no comprehensive national resource reporting hospital cancer surgical volume publicly. We evaluated whether Fee-for-service (FFS) Medicare claims data is representative of hospital all-payer cancer surgery volume and whether we could leverage the data to accurately predict hospital all-payer volume. Methods: We utilized FFS Medicare claims data matched to state inpatient discharge data by hospital for six states and identified cancer-directed surgeries between 2011 and 2013. We first evaluated the representativeness of FFS Medicare of all-payer volume by inspecting scatterplots and calculating correlations. We additionally assessed the change in quartile rank when classifying hospitals by FFS Medicare as compared to all-payer volume. Second, we developed a model to predict all-payer volume from FFS Medicare volume and other possible predictors. Results: There is a positive correlation between FFS Medicare and all-payer volume for cancer-directed surgeries (r=0.92). When considering hospitals FFS Medicare and all-payer volume quartile ranks, most did not change quartiles (71.2%) or moved only one quartile (27%). In using our model to predict hospital volume, the correlation was high between the predicted and observed all-payer volume (r=0.92). However, the average difference between predicted and observed volume was 42.0 (standard deviation 67.0) and was less accurate for low-volume hospitals. Conclusions: Our study found support that FFS Medicare volume is representative of all-payer volume. However, estimates of all-payer volume using FFS Medicare data may be less accurate for low volume hospitals.