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A gradient-boosted model analysis of the impact of body mass index on the short-term outcomes of critically ill medical patients.

Zampieri FG, Colombari F - Rev Bras Ter Intensiva (2015 Apr-Jun)

Bottom Line: A low value (< 20kg/m2) was associated with a sharp increase in hospital mortality.Mortality increased as the burden of comorbidities increased and as the performance status decreased.This association was independent of comorbidities and performance status.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Terapia Intensiva, Hospital Alemão Oswaldo Cruz, São Paulo, SP, Brasil.

ABSTRACT

Objective: To evaluate the impact of body mass index on the short-term prognosis of non-surgical critically ill patients while controlling for performance status and comorbidities.

Methods: We performed a retrospective analysis on a two-year single-center database including 1943 patients. We evaluated the impact of body mass index on hospital mortality using a gradient-boosted model that also included comorbidities and was assessed by Charlson's comorbidity index, performance status and illness severity, which was measured by the SAPS3 score. The SAPS3 score was adjusted to avoid including the same variable twice in the model. We also assessed the impact of body mass index on the length of stay in the hospital after intensive care unit admission using multiple linear regressions.

Results: A low value (< 20kg/m2) was associated with a sharp increase in hospital mortality. Mortality tended to subsequently decrease as body mass index increased, but the impact of a high body mass index in defining mortality was low. Mortality increased as the burden of comorbidities increased and as the performance status decreased. Body mass index interacted with the impact of SAPS3 on patient outcome, but there was no significant interaction between body mass index, performance status and comorbidities. There was no apparent association between body mass index and the length of stay at the hospital after intensive care unit admission.

Conclusion: Body mass index does appear to influence the shortterm outcomes of critically ill medical patients, who are generally underweight. This association was independent of comorbidities and performance status.

No MeSH data available.


Related in: MedlinePlus

Relative influence of each variable of interest on patient outcome.SAPS3adj - Simplified Acute Physiology Score 3 adjusted; BMI - body mass index;CCI - Charlson´s comorbidity index; LOS - length of stay; PS - performancestatus.
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f02: Relative influence of each variable of interest on patient outcome.SAPS3adj - Simplified Acute Physiology Score 3 adjusted; BMI - body mass index;CCI - Charlson´s comorbidity index; LOS - length of stay; PS - performancestatus.

Mentions: All variables elected for the GBM were retained by the model after the analysis. Thefinal model had 3550 trees. The model had a high discriminative capability with an areaunder the receiver operator characteristic (ROC) curve of 0.91. The relative influenceof each variable on the outcome is shown in figure2. BMI was the third most important determinant of the outcome after SAPS3adjand age, accounting for 9.48% of all the influence in the model. SAPS3adj had a relativeinfluence above 50%, and age had a relative influence of 10.4%. Comorbidities,temperature at admission and LOS before ICU admission had similar influences on theoutcome (7.43%, 7.3% and 7.19%, respectively). The effect of BMI on death probability,with all other variables fixed at their mean values, is shown in figure 3. The death probability increased significantly for a BMIbelow 20kg/m2 and then tended to marginally decrease as BMI increased,although its influence was small beyond 22kg/m2. The partial dependence plotsfor age, SAPS3adj, CCI, temperature at admission, LOS before ICU admission, PS, sepsisand steroid use are shown in the electronic supplementary material (Figures S1 to S9,respectively).


A gradient-boosted model analysis of the impact of body mass index on the short-term outcomes of critically ill medical patients.

Zampieri FG, Colombari F - Rev Bras Ter Intensiva (2015 Apr-Jun)

Relative influence of each variable of interest on patient outcome.SAPS3adj - Simplified Acute Physiology Score 3 adjusted; BMI - body mass index;CCI - Charlson´s comorbidity index; LOS - length of stay; PS - performancestatus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489782&req=5

f02: Relative influence of each variable of interest on patient outcome.SAPS3adj - Simplified Acute Physiology Score 3 adjusted; BMI - body mass index;CCI - Charlson´s comorbidity index; LOS - length of stay; PS - performancestatus.
Mentions: All variables elected for the GBM were retained by the model after the analysis. Thefinal model had 3550 trees. The model had a high discriminative capability with an areaunder the receiver operator characteristic (ROC) curve of 0.91. The relative influenceof each variable on the outcome is shown in figure2. BMI was the third most important determinant of the outcome after SAPS3adjand age, accounting for 9.48% of all the influence in the model. SAPS3adj had a relativeinfluence above 50%, and age had a relative influence of 10.4%. Comorbidities,temperature at admission and LOS before ICU admission had similar influences on theoutcome (7.43%, 7.3% and 7.19%, respectively). The effect of BMI on death probability,with all other variables fixed at their mean values, is shown in figure 3. The death probability increased significantly for a BMIbelow 20kg/m2 and then tended to marginally decrease as BMI increased,although its influence was small beyond 22kg/m2. The partial dependence plotsfor age, SAPS3adj, CCI, temperature at admission, LOS before ICU admission, PS, sepsisand steroid use are shown in the electronic supplementary material (Figures S1 to S9,respectively).

Bottom Line: A low value (< 20kg/m2) was associated with a sharp increase in hospital mortality.Mortality increased as the burden of comorbidities increased and as the performance status decreased.This association was independent of comorbidities and performance status.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Terapia Intensiva, Hospital Alemão Oswaldo Cruz, São Paulo, SP, Brasil.

ABSTRACT

Objective: To evaluate the impact of body mass index on the short-term prognosis of non-surgical critically ill patients while controlling for performance status and comorbidities.

Methods: We performed a retrospective analysis on a two-year single-center database including 1943 patients. We evaluated the impact of body mass index on hospital mortality using a gradient-boosted model that also included comorbidities and was assessed by Charlson's comorbidity index, performance status and illness severity, which was measured by the SAPS3 score. The SAPS3 score was adjusted to avoid including the same variable twice in the model. We also assessed the impact of body mass index on the length of stay in the hospital after intensive care unit admission using multiple linear regressions.

Results: A low value (< 20kg/m2) was associated with a sharp increase in hospital mortality. Mortality tended to subsequently decrease as body mass index increased, but the impact of a high body mass index in defining mortality was low. Mortality increased as the burden of comorbidities increased and as the performance status decreased. Body mass index interacted with the impact of SAPS3 on patient outcome, but there was no significant interaction between body mass index, performance status and comorbidities. There was no apparent association between body mass index and the length of stay at the hospital after intensive care unit admission.

Conclusion: Body mass index does appear to influence the shortterm outcomes of critically ill medical patients, who are generally underweight. This association was independent of comorbidities and performance status.

No MeSH data available.


Related in: MedlinePlus