Dataset Information

Examining the robustness of the obesity paradox in maintenance hemodialysis patients: a marginal structural model analysis.

ABSTRACT:

Background

The inverse association between body mass index (BMI) and mortality observed in patients treated with maintenance hemodialysis (MHD), also known as the obesity paradox, may be a result of residual confounding. Marginal structural model (MSM) analysis, a technique that accounts for time-varying confounders, may be more appropriate to investigate this association. We hypothesize that after applying MSM, the inverse association between BMI and mortality in MHD patients is attenuated.

Methods

We examined the associations between BMI and all-cause mortality among 123 624 adult MHD patients treated during 2001-6. We examined baseline and time-varying BMI using Cox proportional hazards models and MSM while considering baseline and time-varying covariates, including demographics, comorbidities and markers of malnutrition and inflammation.

Results

The patients included 45% women and 32% African Americans with a mean age of 61(SD 15) years. In all models, BMI showed a linear incremental inverse association with mortality. Compared with the reference (BMI 25 to <27.5 kg/m(2)), a BMI of <18 kg/m(2) was associated with a 3.2-fold higher death risk [hazard ratio (HR) 3.17 (95% CI 3.05-3.29)], and mortality risks declined with increasing BMI with the greatest survival advantage of 31% lower risk [HR 0.69 (95% CI 0.64-0.75)] observed with a BMI of 40 to <45 kg/m(2).

Conclusions

The linear inverse relationship between BMI and mortality is robust across models including MSM analyses that more completely account for time-varying confounders and biases.

SUBMITTER: Doshi M

PROVIDER: S-EPMC4967726 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Publications

Examining the robustness of the obesity paradox in maintenance hemodialysis patients: a marginal structural model analysis.

Doshi Megha M Streja Elani E Rhee Connie M CM Park Jongha J Ravel Vanessa A VA Soohoo Melissa M Moradi Hamid H Lau Wei Ling WL Mehrotra Rajnish R Kuttykrishnan Sooraj S Kovesdy Csaba P CP Kalantar-Zadeh Kamyar K Chen Joline L T JL

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 20151119 8

<h4>Background</h4>The inverse association between body mass index (BMI) and mortality observed in patients treated with maintenance hemodialysis (MHD), also known as the obesity paradox, may be a result of residual confounding. Marginal structural model (MSM) analysis, a technique that accounts for time-varying confounders, may be more appropriate to investigate this association. We hypothesize that after applying MSM, the inverse association between BMI and mortality in MHD patients is attenua ...[more]

PMID: 26590266

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Project description:BackgroundIn contrast to the general population, higher body mass index (BMI) is associated with greater survival in patients receiving hemodialysis (HD; "obesity paradox"). We hypothesized that this paradoxical association between BMI and death may be modified by age and dialysis vintage.Study designRetrospective observational study using a large HD patient cohort.Setting & participants123,383 maintenance HD patients treated in DaVita dialysis clinics between July 1, 2001, and June 30, 2006, with follow-up through September 30, 2009.PredictorsAge, dialysis vintage, and time-averaged BMI. Time-averaged BMI was divided into 6 subgroups; <18.5, 18.5-<23.0, 23.0-<25.0, 25.0-<30.0, 30.0-<35.0, and ≥35.0kg/m(2). BMI category of 23-<25kg/m(2) was used as the reference category.OutcomesAll-cause, cardiovascular, and infection-related mortality.ResultsMean BMI of study participants was 27±7kg/m(2). Time-averaged BMI was <18.5 and ≥35kg/m(2) in 5% and 11% of patients, respectively. With progressively higher time-averaged BMI, there was progressively lower all-cause, cardiovascular, and infection-related mortality in patients younger than 65 years. In those 65 years or older, even though overweight/obese patients had lower mortality compared with underweight/normal-weight patients, sequential increases in time-averaged BMI > 25kg/m(2) added no additional benefit. Based on dialysis vintage, incident HD patients had greater all-cause and cardiovascular survival benefit with a higher time-averaged BMI compared with the longer term HD patients.LimitationsCausality cannot be determined, and residual confounding cannot be excluded given the observational study design.ConclusionsHigher BMI is associated with lower death risk across all age and dialysis vintage groups. This benefit is more pronounced in incident HD patients and those younger than 65 years. Given the robustness of the survival advantage of higher BMI, examining interventions to maintain or even increase dry weight in HD patients irrespective of age and vintage are warranted.

Dataset Information

Examining the robustness of the obesity paradox in maintenance hemodialysis patients: a marginal structural model analysis.

Background

Methods

Results

Conclusions

Publications

Examining the robustness of the obesity paradox in maintenance hemodialysis patients: a marginal structural model analysis.

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