Fluctuations in BMI linked to worse prognosis for patients with nondialysis-dependent CKD
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Greater variability in BMI, as well as fluctuations in other metabolic components, led to an increased risk of mortality, myocardial infarction, stroke and need for dialysis in a cohort of South Korean patients with chronic kidney disease.
Of the assessed metabolic components — which included waist circumference, fasting blood glucose, blood pressure, serum triglycerides and cholesterol — variability in fasting blood glucose was most strongly associated with the adverse outcomes.
“We extended our assessment to various metabolic parameters, because BMI variability was likely to be closely linked to variabilities in metabolic syndrome components,” Sehoon Park, MD, of Seoul National University College of Medicine, and colleagues wrote. “ ... These findings may encourage clinicians in the nephrology field to carefully assess not only baseline BMI or metabolic status in patients with CKD, but also the fluctuating status of metabolic parameters, due to their potential prognostic significance in such patients.”
Retrospective observational study
Utilizing a national health screening database, Park and colleagues identified 84,636 individuals with a persistent eGFR of less than 60 mL/min/1.73 m2 or a dipstick albuminuria measurement of at least 1 (median age was 68 years and median BMI was 24.6 kg/m2). Patients with prevalent end-stage kidney disease, myocardial infarction or stroke were excluded.
“In this study, BMI variability was identified on the basis of the BMI calculated at every health screening visit. The health screenings also involve laboratory tests and waist circumference measurements to assess major metabolic syndrome components,” the researchers wrote of the study methods. “Pre-dialysis CKD was identifiable on the basis of serum creatinine levels and dipstick albuminuria, which were measured at every health screening visit with [at least] 1-year intervals, and insurance codes specified ESKD events.”
During a median follow-up of 4 years, 6% of the study population died, 4% began maintenance kidney replacement therapy, 3% had a stroke and 2% experienced a myocardial infarction.
Prognostic value of BMI, metabolic variability
Results indicated that patients in the highest quartile of BMI variability had a 60% increased risk for all-cause mortality and were 20% more likely to experience myocardial infarction, stroke or to begin kidney replacement therapy (hazard ratios of 1.66 for mortality and 1.19 for the other outcomes). Researchers noted these findings remained consistent even after adjusting for baseline BMI and eGFR, as well as eGFR variability during the assessment period.
Specific findings related to metabolic components showed patients with higher variability in waist circumference, fasting blood glucose, blood pressure (systolic and diastolic) and cholesterol (LDL, HDL and total) were at an increased risk for all-cause mortality, while those with higher variations in fasting blood glucose and total cholesterol were at an increased risk for starting kidney replacement therapy. Fluctuations in fasting blood glucose also led to greater risk for stroke and myocardial infarction.
Further observations suggested that prognosis differed based on cumulative metabolic variability score — determined by “summing the number of parameters from among BMI, fasting blood glucose, systolic BP, and total cholesterol that had high variability” — with patients who had a higher burden of metabolic variability experiencing worse outcomes.
“In conclusion, high BMI variability is associated with a worse prognosis in patients with pre-dialysis CKD. In addition to the assessment of metabolic status at a single time point, health care providers in the field of nephrology should pay attention to recent trends in metabolic parameters in CKD patients, because a higher degree of fluctuation may be associated with future risks of mortality or major adverse outcomes,” Park and colleagues wrote.
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