Hospital volume, length of stay, and readmission rates in high-risk surgery

Abstract

Objective: Aimed at reducing surgical deaths, several recent initiatives have attempted to establish volume-based referral strategies in high-risk surgery. Although payers are leading the most visible of these efforts, it is unknown whether volume standards will also reduce resource use.

Methods: We studied postoperative length of stay and 30-day readmission rate after 14 cardiovascular and cancer procedures using the 1994-1999 national Medicare database (total n = 2.5 million). We used regression techniques to examine the relationship between length of stay, 30-day readmission, and hospital volume, adjusting for age, gender, race, comorbidity score, admission acuity, and mean social security income.

Results: Mean postoperative length of stay ranged from 3.4 days (carotid endarterectomy) to 19.6 days (esophagectomy). There was no consistent relationship between volume and mean length of stay; it significantly increased across volume strata for 7 of the 14 procedures and significantly decreased across volume strata for the other 7. Mean length of stay at very-low-volume and very-high-volume hospitals differed by more than 1 day for 6 procedures. Of these, the mean length of stay was shorter in high-volume hospitals for 3 procedures (pancreatic resection, esophagectomy, cystectomy), but longer for other procedures (aortic and mitral valve replacement, gastrectomy). The 30-day readmission rate also varied widely by procedure, ranging from 9.9% (nephrectomy) to 22.2% (mitral valve replacement). However, volume was not related to 30-day readmission rate with any procedure.

Conclusion: Although hospital volume may be an important predictor of operative mortality, it is not associated with resource use as reflected by length of stay or readmission rates.

FIGURE 1. (a) Mean postoperative length of stay for 6 cardiovascular procedures, based on data from the national Medicare population (1994–1999). P < 0.05 for all differences across volume strata. (b) Mean postoperative length of stay for 8 cancer resections, based on data from the national Medicare population (1994–1999). P < 0.05 for all differences across volume strata.