Body mass index and causes of death in chronic kidney disease

Area of Science:

• Nephrology
• Epidemiology
• Public Health

Background:

• Higher body mass index (BMI) in chronic kidney disease (CKD) patients is linked to lower overall mortality.
• Specific causes of death across the BMI spectrum in CKD patients remain unclear.
• Understanding these associations is crucial for risk stratification and management.

Purpose of the Study:

• To investigate the relationship between BMI and cause-specific mortality in a large cohort of CKD patients.
• To define the association between various BMI categories and cardiovascular, malignancy, and noncardiovascular/nonmalignancy-related deaths.
• To identify potential protective effects of higher BMI within the CKD population.

Main Methods:

• Retrospective analysis of 54,506 CKD patients (91.5% stage 3 CKD) from an institutional electronic medical record registry.
• Utilized Cox proportional hazards and competing risks regression models to assess mortality risks.
• Examined associations between BMI ranges (normal, overweight, obesity classes 1-3) and specific causes of death over a median follow-up of 3.7 years.

Main Results:

• An inverted J-shaped association was observed between BMI and cardiovascular, malignancy, and noncardiovascular/nonmalignancy-related deaths.
• Overweight (BMI 25-29.9 kg/m²), class 1 (30-34.9 kg/m²), and class 2 (35-39.9 kg/m²) obesity were associated with a lower risk of all-cause mortality compared to normal BMI (18.5-24.9 kg/m²).
• BMI >40 kg/m² did not show an association with cardiovascular or noncardiovascular/nonmalignancy deaths.

Conclusions:

• In CKD patients, being overweight or having class 1 or 2 obesity is associated with a reduced risk of death from cardiovascular, malignancy, and other causes compared to normal BMI.
• These findings suggest a complex relationship between adiposity and mortality in CKD.
• Further research into other measures of adiposity and their impact on CKD outcomes is warranted.