NIS vs SAGES: a comparison of national and voluntary databases

Surgical outcomes are increasingly examined in an effort to improve quality and reduce medical error. The Nationwide Inpatient Sample (NIS) is a retrospective, claims-derived and population-based database and the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) Outcomes Project is a prospective, voluntary and specialty surgeon database. We hypothesized that these two sources of outcome data would differ in regard to a single, commonly performed procedure.

Both the NIS, a national sample of all nonfederal hospital discharges, and the gastroesophageal reflux disease log of the SAGES Outcomes Project were queried for all fundoplications performed between 1999 and 2001 using either ICD-9 procedure code 44.66 or CPT codes 43280 or 43324. Patients with an emergency admission, age <17 years, and/or diagnoses for either esophageal cancer or achalasia were excluded. Both demographic and outcome variables were compared by either t-test or chi-square analysis, with a p value of <0.05 as significant.

Both data sets were comparable for age and gender; however, the SAGES group had a higher rate of teaching hospital affiliation (71 vs 48%, p < 0.001). SAGES fundoplications had a consistently higher rate of comorbidities, including Barrett's esophagus (2.3 vs 1.1%, p = 0.005). The NIS fundoplications had a clear trend toward more associated procedures, including cholecystectomy (7.2 vs 2%, p < 0.001). Complication rates for the NIS data set were higher, including pulmonary complications (1.7 vs 0.5%, p = 0.03). No statistically significant differences existed between the two data sets for either length of stay or mortality.

The two databases indicate that fundoplication is an operation with low morbidity and mortality. The SAGES Outcomes Project demonstrated that participating surgeons had a higher affiliation with teaching hospitals, higher reporting of comorbidity, and lower associated procedures than the NIS. Despite having more comorbidity and technical difficulty, patients from the SAGES Outcomes Project had equivalent or lower complication rates.