Hospital volume and patient outcomes in hepato-pancreatico-biliary surgery: is assessing differences in mortality enough?

BACKGROUND: The impact of regionalization on morbidity, failure to rescue (FTR), length of stay (LOS), and readmission remains unclear. We sought to examine hospital-volume-related differences in outcomes following complex hepato-pancreatico-biliary (HPB) surgery and define potential benefits of regionalization across quality metrics.
METHODS: Patients undergoing HPB surgery in the Surveillance, Epidemiology and End Results (SEER)-Medicare linked data from 1986 to 2002 were identified. Hospital volume was stratified into tertiles (low volume [LV] <4 cases/year; intermediate volume [IV] 4-10 cases/year; high volume [HV] ≥11 cases/year). The incidence of complications, FTR (mortality following a complication), and LOS was compared across hospital-volume strata. A counterfactual model examined hypothetical outcomes assuming all patients had been treated at HV centers.
RESULTS: Ten thousand two hundred eight patients underwent pancreatic (46.1 %), hepatic (36.2 %), or biliary (17.8 %) procedures. Overall mean age ranged from 72.7 years at HV centers to 73.4 at LV centers (P < 0.001), and patients at HV centers (75.4 %) were more likely to have ≥3 comorbidities versus IV (70.0 %) or LV (64.7 %) centers (P < 0.001). The incidence of post-operative complications was lower at HV (39.1 %) compared with IV (41.9 %) or LV (44.8 %) centers. Major complications included hemorrhagic anemia (7.3 %), failure to thrive (5.1 %), and respiratory infection/failure (3.5 %); each was less common in HV hospitals (P < 0.05). FTR after major complication tended to be higher at LV (36.7 %) and IV (37.3 %) hospitals compared with HV hospitals (29.7 %) (P = 0.10). Mortality was higher at LV (10.5 %) and IV (8.1 %) hospitals versus HV centers (5.4 %) (P < 0.001). HV hospital patients had shorter median LOS (10 days) compared with IV (12 days) or LV (12 days) hospital patients (P < 0.001). Readmission varied across centers (HV 19.1 % vs. IV 19.2 % vs. 16.7 %; P = 0.02). In a counterfactual model with all patients treated at a HV center, 6.4 % fewer complications and a 26.0 % increase in post-complication rescue would be expected, along with a 32.0 % reduction in index mortality and an 8.1 % reduction in total patient-days. A minor increase in readmissions (7.1 %) would be anticipated with 13.3 % fewer deaths during readmission.
CONCLUSION: Although patients treated at HV hospitals had more medical comorbidities, outcomes across a wide spectrum of quality metrics were better than at IV or LV hospital following complex HPB surgery. A 20-30 % reduction in morbidity and mortality and an 8 % reduction in hospital patient-days could be anticipated had all patients been treated at HV hospitals.