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BMC Nephrol. 2018 Feb 7;19(1):32. doi: 10.1186/s12882-018-0833-5.

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.

Author information

1
Department of Internal Medicine, Institute of Kidney Disease Research, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-Gu, Seoul, 03722, South Korea.
2
Division of Nephrology, Soonchunhyang University, Seoul, Republic of Korea.
3
Ewha Institute of Convergence Medicine, Ewha Womans University Mokdong Hospital, Seoul, Republic of Korea.
4
Division of Nephrology, Department of Internal Medicine, National Health Insurance Service Medical Center, Ilsan Hospital, Goyang, Gyeonggi-do, Republic of Korea.
5
Department of Internal Medicine, Institute of Kidney Disease Research, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-Gu, Seoul, 03722, South Korea. hansh@yuhs.ac.

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.

KEYWORDS:

Acute kidney injury; Body mass index; Continuous renal replacement therapy; Disease severity; Mortality

PMID:
29415663
PMCID:
PMC5804063
DOI:
10.1186/s12882-018-0833-5
[Indexed for MEDLINE]
Free PMC Article

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