Body mass index and acute kidney injury in the acute respiratory distress syndrome.
OBJECTIVE
Obesity is increasingly encountered in intensive care units but the relationship between obesity and acute kidney injury is unclear. We aimed to evaluate whether body mass index was associated with acute kidney injury in the acute respiratory distress syndrome and to examine the association between acute kidney injury and mortality in patients with and without obesity.


METHODS
Retrospective study.


METHODS
Massachusetts General Hospital and Beth Israel Deaconess Medical Center.


METHODS
Seven hundred fifty-one patients with acute respiratory distress syndrome.


METHODS
None.


RESULTS
Acute kidney injury was defined as meeting the "Risk" category according to modified Risk, Injury, Failure, Loss, End-stage criteria based on creatinine and glomerular filtration rate because urine output was only available on the day of intensive care unit admission. Body mass index was calculated from height and weight at intensive care unit admission. The prevalence of acute kidney injury increased significantly with increasing weight (p = .01). The odds of acute kidney injury were twice in obese and severely obese patients compared to patients with normal body mass index, after adjusting for predictors of acute kidney injury (age, diabetes, Acute Physiology and Chronic Health Evaluation III, aspiration, vasopressor use, and thrombocytopenia [platelets ≤ 80,000/mm]). After adjusting for the same predictors, body mass index was significantly associated with acute kidney injury (odds ratio(adj) 1.20 per 5 kg/m increase in body mass index, 95% confidence interval 1.07-1.33). On multivariate analysis, acute kidney injury was associated with increased acute respiratory distress syndrome mortality (odds ratio(adj) 2.76, 95% confidence interval 1.72-4.42) whereas body mass index was associated with decreased mortality (odds ratio(adj) 0.81 per 5 kg/m increase in body mass index, 95% confidence interval 0.71-0.93) after adjusting for mortality predictors.


CONCLUSIONS
In acute respiratory distress syndrome patients, obesity is associated with increased development of acute kidney injury, which is not completely explained by severity of illness or shock. Although increased body mass index is associated with decreased mortality, acute kidney injury remained associated with higher mortality even after adjusting for body mass index.
Division of Critical Care Medicine, Jay B. Langner Critical Care Service, Department of Medicine, Montefiore Medical Center, Bronx, NY 10467, USA. gsoto@montefiore.org
Graciela J
GJ
Soto
Angela J
AJ
Frank
David C
DC
Christiani
Michelle Ng
MN
Gong
D000046:Academic Medical Centers; D058186:Acute Kidney Injury / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015992:Body Mass Index; D002423:Cause of Death; D015331:Cohort Studies; D015897:Comorbidity; D016001:Confidence Intervals; D003422:Critical Care / Q000379:methods; D016638:Critical Illness / Q000401:mortality / Q000628:therapy; D005260:Female; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units; D008297:Male; D008404:Massachusetts; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D016017:Odds Ratio; D011379:Prognosis; D012016:Reference Values; D012128:Respiratory Distress Syndrome / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis; D016896:Treatment Outcome