Comparison of risk factors for length of stay and readmission following lower extremity bypass surgery

Objective: Recent initiatives to improve health care quality have focused attention on length of stay (LOS) and readmission rates for surgical patients, yet these two outcomes may be inversely related. This study was designed to elucidate the risk factors for both outcomes and to clarify the relationship between them in patients undergoing lower extremity bypass (LEB). Methods: Peripheral arterial disease (PAD) patients who underwent LEB were identified from the 2007-2010 California State Inpatient Database. LOS and risk factors were analyzed using Poisson regression. Risk factors for 30-day readmission were analyzed using logistic regression. Results: There were 6307 patients who underwent LEB, and 1291 (20%) were readmitted. The average index LOS was 8.3 days for those who were readmitted and 5.5 days for those who were not (P <.0001) and was an independent risk factor for 30-day readmission. The significant factors with the largest effect estimates for increased LOS reflected disease severity and postoperative complications: emergency department admission; advanced PAD; postoperative pneumonia, respiratory failure, urinary tract infection, wound/graft infection, graft complication, and discharge to a nursing facility. Independent predictors of readmission, other than LOS, reflected underlying patient factors: advanced PAD, chronic lung disease, diabetes, renal failure, postoperative congestive heart failure, and discharge status. Age, Medicaid or private insurance, and low income were protective. Of the 1291 readmissions, 453 (35%) were for definitive complications. Conclusions: In patients undergoing LEB, LOS is primarily associated with the occurrence of postoperative complications, whereas 30-day readmission is largely explained by underlying patient illness. Additionally, increased LOS is an independent risk factor for readmission. These findings suggest that efforts to reduce both LOS and readmission will be complementary. Furthermore, they support the notion that both LOS and 30-day readmission rates should be risk-adjusted.