Obesity and Mortality Risk among Younger Dialysis Patients

Abstract

SummaryBackground and objectives Many studies show that obesity in dialysis patients is not strongly associated with mortality but not whether this modest association is constant over age. This study investigated the extent to which the relation of body mass index (BMI) and mortality differs between younger and older dialysis patients.Design, setting, participants, & measurements Adult dialysis patients were prospectively followed from their first dialysis treatment for 7 years or until death or transplantation. Patients were stratified by age (,65 or $65 years) and baseline BMI (,20, 20-24 [reference], 25-29, and $30 kg/m 2 ).Results The study sample included 984 patients younger than 65 years and 765 patients 65 years or older; cumulative survival proportions at end of follow-up were 50% and 16%. Age-standardized mortality rate was 1.7 times higher in obese younger patients than those with normal BMI, corresponding to an excess rate of 5.2 deaths/100 patient-years. Mortality rates were almost equal between obese older patients and those with normal BMI. Excess rates of younger and older patients with low compared with normal BMI were 8.7 and 1.1 deaths/100 patient-years. After adjustment for age, sex, smoking, comorbidity, and treatment modality, hazard ratios by increasing BMI were 2.00, 1, 0.95, and 1.57 for younger patients and 1.07, 1, 0.88, and 0.91 for older patients, implying that obesity is a 1.7-fold (95% confidence interval, 1.1-to 2.9-fold) stronger risk factor in younger than older patients.Conclusions In contrast to older dialysis patients, younger patients with low or very high BMI had a substantially elevated risk for death.

Does the Obesity Survival Paradox of Dialysis Patients Differ with Age?

“…First, de Mutsert et al [29], in a 2007 study of 722 incident dialysis patients between 50 and 65 years with a seven-year observation period, found that the association between BMI and mortality is not reversed and concluded that the duration and age must be taken into account when interpreting the association between obesity and survival. Hoogeveen et al [20], in another analysis of the NECOSAD in 2012, divided patients into older or younger than 65 years and concluded that younger patients with a high BMI, as is the case with the general population, had higher death rates than those with normal BMI and that among older patients there were similar death rates between the obese and those with normal BMI. This disparity with the results of earlier studies is attributed by the authors to reasons such as too short a period of observation, the inclusion of prevalent dialysis patients, and the combination of results between younger and older patients, among others.…”

“…A recent study suggested an effect modification of this phenomenon by age: in a cohort of incident dialysis patients from the Netherlands, the obesity paradox was observed only among elderly individuals, and obesity behaved as a mortality risk factor in younger patients (<65 years) [20]. Confirmation of this observation is important, as it may motivate different therapeutic body weight measures in this heterogeneous population.…”

Preventive Nephrology: The Role of Obesity in Different Stages of Chronic Kidney Disease

“…In older age groups, hemodialysis patients with stable weight had a longer survival than elderly who lose or gain weight [30]. Death rates of obese younger dialysis patients (< 65 years) are 1.7-fold higher than for the older group (> 65 years) after adjustment for comorbidity and treatment modality [31].…”

Obesity and Kidney Transplant Candidates: How Big Is Too Big for Transplantation?

“…There is also emerging evidence that this ‘reverse epidemiology’ may not be present in all subgroups. For example, a new study that followed adult dialysis patients from the first dialysis treatment until 7 years, death, or kidney transplant found that while older dialysis patients had ‘reverse epidemiology’ for BMI, younger patients with a high BMI had 1.7 times the standardized mortality of young patients with normal BMI, mirroring typical general population patterns [23]. …”