Background: Commonly performed elective gastrointestinal surgical procedures are carried out with low morbidity and mortality in hospitals throughout the United States. Complex operative procedures on the alimentary tract are performed with a relatively low frequency and are associated with higher mortality. Volume and experience of the surgical provider team have been correlated with better clinical and economic outcomes for one complex gastrointestinal surgical procedure, pancreaticoduodenectomy. This study evaluated whether provider volume and experience were important factors influencing clinical and economic outcomes for a variety of complex gastrointestinal surgical procedures in one state.
Study design: Complex high-risk gastrointestinal surgical procedures were defined as those with statewide in-hospital mortality of > or = 5%, frequency of greater than 200 per year in the state, and requiring special surgical skill and expertise. Six procedures met these criteria. Using publicly available discharge data, all patients discharged from Maryland hospitals from July 1989 to June 1997 with a primary procedure code for one of the six study procedures were selected. Hospitals were classified into one of six groups based on the average number of study procedures per year: 10 or less; 11 to 20; 21 to 50; 51 to 100; 101 to 200; and 201 or more procedures per year. A hospital was included if at least one procedure was performed there during the study period. No providers fell within the 51 to 100, and 101 to 200 groups, so all analyses were performed for the remaining four volume groups that were classified, respectively, as minimal (10 or fewer procedures), low (11 to 20 procedures), medium (21 to 50 procedures), and high-volume groups (201 or more procedures). Poisson regression was used to assess the relationship between in-hospital mortality and hospital volume after case-mix adjustment. Multiple linear regression models were used to assess differences in average length-of-stay and average total hospital charges among hospital volume groups. We further analyzed mortality, length-of-stay, and charges at the procedural level to understand these subgroups of complex gastrointestinal patients. We also examined the relationship between provider volume and outcomes for malignant versus benign diagnosis groups.
Results: Complex gastrointestinal surgical procedures were performed on 4,561 patients in Maryland from July 1989 through June 1997. The study population averaged 61.6 years of age, was 55% male, 71% Caucasian, and had predominantly Medicare as a payment source. After case-mix adjustment, patients who underwent complex gastrointestinal surgical procedures at the medium-, low-, and minimal-volume provider groups had a 2.1, 3.3, and 3.2 times greater risk of in-hospital death, respectively, than patients at the high-volume provider (p < 0.001 for all comparisons); longer lengths-of-stay, 16.1, 15.7, and 15.5 days at the low-, medium-, and minimal-volume groups, respectively, versus 14.0 days for the high-volume provider (p < 0.001 for all comparisons). Similarly, adjusted charges at the high-volume provider were, on average, 14% less than those of the low-volume group, which had the next lowest charges. Although mortality rates differed by procedure type, for each procedure, mortality increased as provider volume decreased, following the pattern found in the aggregate analysis. After case-mix adjustment, the risk of in-hospital death for patients with malignant diagnoses was significantly higher for the medium-, low-, and minimal-volume groups compared with patients at the high-volume provider, relative risk of 3.1, 4.0, and 4.2, respectively, (p < 0.001 for all comparisons).
Conclusions: This study demonstrates that increased hospital experience is associated with a marked decrease in hospital mortality. The decreased mortality at the high-volume provider was also associated with shorter lengths-of-stay and lower hospital char