This article is written live from ID Week 2017 Annual Meeting in San Diego, CA. MPR will be reporting news on the latest findings from leading experts in infectious diseases. Check back for more news from IDWeek 2017.

SAN DIEGO—Obesity might increase the risk of acute kidney injury (AKI) among patients receiving concomitant piperacillin-tazobactam (TZP) and vancomycin (VAN), according to research findings presented at IDWeek 2017.

“Obesity appears to increase the incidence of AKI among patients treated with TZP+VAN, independent of clinically important confounders, with an important breakpoint occurring at 91kg,” reported study coauthor W. Cliff Rutter, PharmD, MS, of the University of Kentucky College of Pharmacy, in Lexington, KY.

The coauthors gathered clinical and demographic data for patients who received TZP+VAN for 48 hours or more, using the University of Kentucky Center for Clinical and Translational Science Enterprise Data Trust.

“Patients with CKD, a baseline creatinine clearance (CrCl) <30mL/min, CF, or missing height and weight information were excluded from analysis,” Dr. Rutter said. “AKI was defined using the Risk, Injury, Failure, Loss, End-stage (RIFLE) criteria.”

Regression analysis was performed to identify a weight cutoff point of 91kg. 

“In total, 8125 patients were included in the final analysis,” Dr. Rutter reported. “A total of 2452 (30.2%) of patients weighed ≥91kg.” The researchers found that patients who weighed less 91kg were less likely to receive concomitant nephrotoxins and had higher baseline CrCl (97.3 [70.1–128.1] mL/min vs. 91.8 [68.1–116.5] mL/min, P<0.00001).

“Baseline severity of illness was similar between groups; however, diabetes (38.9% vs. 20.8%, P<0.00001), hypertension (63.5% vs. 46.7%, P<0.00001), and heart failure (14.8% vs. 12.5%, P=0.007) were more common among the 91kg+ patients,” Dr Rutter reported. “Median daily VAN doses were less in the sub-91kg patients (2000 [1250–2500] mg vs. 3000 [2000–3500] mg, P<0.00001); however, weight-based doses were lower in the ≥91kg group (25.5 [16.3–31.5] mg/kg/day vs 27.9 [18.7–34.2] mg/kg/day, P<0.00001). AKI was more common in the patients weighing ≥91kg (23.8% vs. 17.8%, P<0.00001; adjusted odds ratio 1.46 [95% CI 1.28–1.66]).”

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Rutter C, Hall R, Burgess D. Impact of obesity on acute kidney injury incidence among patients treated with piperacillin-tazobactam and vancomycin. Poster presented at IDWeek; October 4–8, 2017; San Diego, CA.