Surgeon work captured by the National Surgical Quality Improvement Program across specialties.

BACKGROUND: The National Surgical Quality Improvement Program (NSQIP) database is increasingly used for surgical research. However, it is unclear how well this database represents the breadth of work performed by different specialties.

METHODS: Using the 2017 NSQIP participant use file and the 2017 Medicare Physician/Supplier Procedure Summary file, we evaluated (1) what proportion of surgical work is captured by NSQIP, (2) what procedures and disciplines are undersampled, and (3) the overall concordance between the NSQIP sample and a national sample.

RESULTS: The NSQIP database reported at least one case for 4,463 out of the 5,272 Current Procedures Terminology codes in the Medicare file, potentially capturing 97.8% of surgical work across all 10 specialties. However, this proportion decreased to 72.1% when only procedures with at least 100 cases in NSQIP were considered. Limiting our analysis to only those procedures with 100 cases had markedly different effects by specialty. In part, this was owing to undersampling of minor procedures, which are more common in disciplines such as otolaryngology and urology. The overall association between the size of the NSQIP sample and the Medicare sample was 0.08.

CONCLUSION: Although NSQIP has the potential to capture a diverse surgical caseload, some specialties and procedures are undersampled, limiting the ability for NSQIP to generate valid benchmarks. There was little correlation between the sample sizes in NSQIP and a national sample. Increasing sampling of underrepresented procedures and developing weights to scale NSQIP to a national sample would strengthen the program's ability to inform health outcomes research and provide valid comparisons across procedures and specialties.