Acute kidney injury in bariatric surgery patients requiring intensive care admission: a state-wide, multicenter, cohort study

Background A multidisciplinary bariatric surgical approach is currently the most effective treatment for obesity. However, little is known about how the physiologic impact of weight reduction surgery superimposed on premorbid obesity-related co-morbidities may adversely influence perioperative renal function. Methods This observational, multicenter study investigated all bariatric surgery patients (n = 590) admitted to any intensive care unit (ICU) in Western Australia between 2007 and 2011. Using Acute Kidney Injury Network (AKIN) criteria, we ascertained the incidence and contributing risk factors for acute kidney injury (AKI). Results Acute kidney injury (AKI) occurred in 103 patients, accounting for 17.5% of all ICU admissions after bariatric surgery with 76.8% of the AKI episodes limited to AKIN stage 1. In a multivariate analysis, male gender, premorbid hypertension, higher admission APACHE II scores, and blood transfusions were all associated with AKI, while preexisting chronic kidney disease and body mass index (BMI) appeared not to influence renal decline. Both ICU (6.7 versus 2.5 d, P<.001) and hospital (18.6 versus 6.8 d, P<.001) length of stays were significantly increased after AKI. Six patients required hemodialysis while both ICU mortality (2.9 versus 0%, P =.005) and long-term mortality (18.2 versus 4.7 deaths per 1000 bariatric patient-yr, P =.01) were greater in patients experiencing AKI. Conclusions AKI is common in bariatric patients requiring critical care support leading to increased healthcare utilization, prolonged hospitalization, and is associated with a higher mortality. BMI, a previously described risk factor, was not predictive of AKI in this cohort