Objectives: Higher body mass index is associated with increased risk of acute kidney injury after major trauma. Since body mass index is nonspecific, reflecting lean, fluid, and adipose mass, we evaluated the use of CT to determine if abdominal adiposity underlies the body mass index-acute kidney injury association.
Design: Prospective cohort study.
Setting: Level I Trauma Center of a university hospital.
Patients: Patients older than 13 years with an Injury Severity Score greater than or equal to 16 admitted to the trauma ICU were followed for development of acute kidney injury over 5 days. Those with isolated severe head injury or on chronic dialysis were excluded.
Measurements and Main Results: Clinical, anthropometric, and demographic variables were collected prospectively. CT images at the level of the L4–5 intervertebral disc space were extracted from the medical record and used by two operators to quantitate visceral adipose tissue and subcutaneous adipose tissue areas. Acute kidney injury was defined by Acute Kidney Injury Network creatinine and dialysis criteria. Of 400 subjects, 327 (81.8%) had CT scans suitable for analysis: 264 of 285 (92.6%) blunt trauma subjects and 63 of 115 (54.8%) penetrating trauma subjects. Visceral adipose tissue and subcutaneous adipose tissue areas were highly correlated between operators (intraclass correlation > 0.99, p < 0.001 for each) and within operator (intraclass correlation > 0.99, p < 0.001 for each). In multivariable analysis, the standardized risk of acute kidney injury was 15.1% (95% CI, 10.6–19.6%), 18.1% (14–22.2%), and 23.1% (18.3–27.9%) at the 25th, 50th, and 75th percentiles of visceral adipose tissue area, respectively (p = 0.001), with similar findings when using subcutaneous adipose tissue area as the adiposity measure.
Conclusions: Quantitation of abdominal adiposity using CT scans obtained for clinical reasons is feasible and highly reliable in critically ill trauma patients. Abdominal adiposity is independently associated with acute kidney injury in this population, confirming that excess adipose tissue contributes to the body mass index-acute kidney injury association. Further studies of the potential mechanisms linking adiposity with acute kidney injury are warranted.
1Pulmonary, Allergy, and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
2Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
3Division of Traumatology, Surgical Critical Care, and Emergency Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
4Drexel University School of Public Health, Philadelphia, PA.
5Renal, Electrolyte, and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
6Cardiovascular Medicine Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
7Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
8Center for Translational Lung Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
* See also p. 1728.
This work was performed at Perelman School of Medicine, University of Pennsylvania.
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Supported, in part, by grants P50-HL60290, P01-HL079063, K24-HL115354, K12-HL090021, K12-HL109009, and K23-DK097307 from the National Institutes of Health.
Drs. Shashaty, Bellamy, John Reilly, Holena, Lanken, Feldman, Muredach Reilly, and Christie report institutional funding from the National Institutes of Health (NIH). Dr. Shashaty’s institution received grant support from the NIH (K12 and K23 career development awards). Dr. Lanken reports textbook royalties from Elsevier. Dr. Feldman reports payment for lectures at Case Western Reserve University and George Washington University and travel/accommodation/meeting expenses from the American College of Epidemiology. Dr. Muredach Reilly reports individual and institutional funding from Merck and GlaxoSmithKline as well as payment for lectures by Merck. Dr. Christie reports payments from various law firms for asbestos litigation as well as institutional funding from GlaxoSmithKline. The remaining authors have disclosed that they do not have any potential conflicts of interest.
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