Severity of Illness Scores May Misclassify Critically Ill Obese Patients*

Abstract

Among patients with the same severity of illness score, we detected clinically small but significant deviations in WBC, creatinine, and blood urea nitrogen from baseline in obese compared with normal weight patients. These small deviations are likely to be increasingly important as bigger data are analyzed in increasingly precise ways. Recognition of the extent to which all critically ill patients may deviate from their own baseline may improve the objectivity, precision, and generalizability of ICU mortality prediction and severity adjustment models.

Critical Care, Critical Data

“…The course, now in its third year, produces numerous abstracts, presentations, and publications and will serve as a model for other courses around the world. [33][34][35][36][37] To promote such efforts, MIT Critical Data has published a textbook for the course, Secondary Analysis of Electronic Health Record Data, and made it freely available as an eBook online. 38 All of these efforts seek to build a bridge between clinician and data scientist that works to improve understanding of health and disease, and ultimately impact patient outcomes.…”

“…The course, now in its third year, produces numerous abstracts, presentations, and publications and will serve as a model for other courses around the world. 33–37 To promote such efforts, MIT Critical Data has published a textbook for the course, Secondary Analysis of Electronic Health Record Data , and made it freely available as an eBook online. 38…”

An Evaluation of the Influence of Body Mass Index on Severity Scoring*

“…While studies that include BMI generally focus on the obese end of the spectrum, the small number of underweight patients in any ICU population (4% in ours) may also prove to be a worthwhile target for future research. We previously reported that SOFA scoring is potentially inaccurate in obese patients because of physiological data anomalies that are present before ICU admission that may lead to deceptively high score values (18). In practice, these falsely high values may be offset by real deficits in physiological reserve among the obese that are not captured by scoring systems.…”

“…In a recent study, we showed that critically ill obese patients could be misclassified by severity of illness scores (18). In that study, we demonstrated that a fundamental assumption of these prognostic models may be flawed in that identical ICU severity scores may reflect changes from disparate baselines when non-identical populations are considered.…”

“…In that study, we demonstrated that a fundamental assumption of these prognostic models may be flawed in that identical ICU severity scores may reflect changes from disparate baselines when non-identical populations are considered. Obese and normal weight ICU patients demonstrated different laboratory deviations from baseline which could potentially lead to errors in predicted mortality (18). In the absence of prior studies on the effect of BMI on severity scores, we hypothesized that these scores would perform differently if BMI was included as a scoring value.…”