The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy

Hyoungnae Kim, Hyunwook Kim, Misol Lee, Min Uk Cha, Ki Heon Nam, Seong Yeong An, Su Young Jung, Jong Hyun Jhee, Seohyun Park, Hae Ryong Yun, Youn Kyung Kee, Hyung Jung Oh, Jung Tak Park, Tae Ik Chang, Tae Hyun Yoo, Shin Wook Kang, Seung Hyeok Han

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Abstract

Background: Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality. Methods: We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m2), normal (18.5-22.99 kg/m2), overweight (23.0-24.99 kg/m2), and obesity (≥25 kg/m2) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT. Results: The mean age was 63.2 years and 439 (38.4%) were females. The median BMI was 23.6 (20.9-26.2) kg/m2. The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P < 0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48-0.76, P < 0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16-2.60; P = 0.007). Conclusion: In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

Original languageEnglish
Article number32
JournalBMC Nephrology
Volume19
Issue number1
DOIs
Publication statusPublished - 2018 Feb 7

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Renal Replacement Therapy
Acute Kidney Injury
Body Mass Index
Mortality
Organ Dysfunction Scores
Sepsis
Thinness
Confidence Intervals
Survival
Obesity
Nutritional Status
Practice Guidelines
Observational Studies
Regression Analysis
Inflammation

All Science Journal Classification (ASJC) codes

  • Nephrology

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Kim, Hyoungnae ; Kim, Hyunwook ; Lee, Misol ; Cha, Min Uk ; Nam, Ki Heon ; An, Seong Yeong ; Jung, Su Young ; Jhee, Jong Hyun ; Park, Seohyun ; Yun, Hae Ryong ; Kee, Youn Kyung ; Oh, Hyung Jung ; Park, Jung Tak ; Chang, Tae Ik ; Yoo, Tae Hyun ; Kang, Shin Wook ; Han, Seung Hyeok. / The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy. In: BMC Nephrology. 2018 ; Vol. 19, No. 1.
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abstract = "Background: Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality. Methods: We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m2), normal (18.5-22.99 kg/m2), overweight (23.0-24.99 kg/m2), and obesity (≥25 kg/m2) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT. Results: The mean age was 63.2 years and 439 (38.4{\%}) were females. The median BMI was 23.6 (20.9-26.2) kg/m2. The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P < 0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95{\%} confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95{\%} CI, 0.48-0.76, P < 0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95{\%} CI, 1.16-2.60; P = 0.007). Conclusion: In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.",
author = "Hyoungnae Kim and Hyunwook Kim and Misol Lee and Cha, {Min Uk} and Nam, {Ki Heon} and An, {Seong Yeong} and Jung, {Su Young} and Jhee, {Jong Hyun} and Seohyun Park and Yun, {Hae Ryong} and Kee, {Youn Kyung} and Oh, {Hyung Jung} and Park, {Jung Tak} and Chang, {Tae Ik} and Yoo, {Tae Hyun} and Kang, {Shin Wook} and Han, {Seung Hyeok}",
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day = "7",
doi = "10.1186/s12882-018-0833-5",
language = "English",
volume = "19",
journal = "BMC Nephrology",
issn = "1471-2369",
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The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy. / Kim, Hyoungnae; Kim, Hyunwook; Lee, Misol; Cha, Min Uk; Nam, Ki Heon; An, Seong Yeong; Jung, Su Young; Jhee, Jong Hyun; Park, Seohyun; Yun, Hae Ryong; Kee, Youn Kyung; Oh, Hyung Jung; Park, Jung Tak; Chang, Tae Ik; Yoo, Tae Hyun; Kang, Shin Wook; Han, Seung Hyeok.

In: BMC Nephrology, Vol. 19, No. 1, 32, 07.02.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy

AU - Kim, Hyoungnae

AU - Kim, Hyunwook

AU - Lee, Misol

AU - Cha, Min Uk

AU - Nam, Ki Heon

AU - An, Seong Yeong

AU - Jung, Su Young

AU - Jhee, Jong Hyun

AU - Park, Seohyun

AU - Yun, Hae Ryong

AU - Kee, Youn Kyung

AU - Oh, Hyung Jung

AU - Park, Jung Tak

AU - Chang, Tae Ik

AU - Yoo, Tae Hyun

AU - Kang, Shin Wook

AU - Han, Seung Hyeok

PY - 2018/2/7

Y1 - 2018/2/7

N2 - Background: Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality. Methods: We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m2), normal (18.5-22.99 kg/m2), overweight (23.0-24.99 kg/m2), and obesity (≥25 kg/m2) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT. Results: The mean age was 63.2 years and 439 (38.4%) were females. The median BMI was 23.6 (20.9-26.2) kg/m2. The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P < 0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48-0.76, P < 0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16-2.60; P = 0.007). Conclusion: In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

AB - Background: Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality. Methods: We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m2), normal (18.5-22.99 kg/m2), overweight (23.0-24.99 kg/m2), and obesity (≥25 kg/m2) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT. Results: The mean age was 63.2 years and 439 (38.4%) were females. The median BMI was 23.6 (20.9-26.2) kg/m2. The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P < 0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48-0.76, P < 0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16-2.60; P = 0.007). Conclusion: In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

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