Weight Loss Helps Preserve Renal Function in Obese Patients with Kidney Disease

Weight loss may help preserve renal function in obese people with kidney disease, according to the results of a systematic review and meta-analysis just published.

Sankar D. Navaneethan, MD, MPH, from Cleveland Clinic in Cleveland, Ohio, and colleagues write, “Obesity is an independent risk factor for development and progression of chronic kidney disease (CKD)…. We conducted a systematic review to assess the benefits of intentional weight loss in patients with non-dialysis-dependent CKD and glomerular hyperfiltration.”

The reviewers performed a literature search of MEDLINE, SCOPUS, and conference proceedings for randomized controlled trials and observational studies evaluating different surgical and nonsurgical interventions, including diet, exercise, and/or antiobesity drugs, in obese adults with CKD. A random-effects model was used to summarize the results of 13 included studies.

At the end of the study period, body mass index (BMI) decreased significantly in patients with CKD who received nonsurgical interventions (weighted mean difference [WMD], -3.67 kg/m²; 95% confidence interval [CI], -6.56 to -0.78 kg/m²). During a mean follow-up of 7.4 months, these patients had a significant decrease in proteinuria (WMD, -1.31 g/24 hours; 95% CI, -2.11 to -0.51 g/24 hours) and in systolic blood pressure (BP), and there was no further decrease in glomerular filtration rate (GFR).

In morbidly obese patients, defined as those in whom BMI was greater than 40 kg/m², with glomerular hyperfiltration (GFR > 125 mL/minute), surgical interventions were associated with decreased BMI. This was associated with decreased GFR (WMD, -25.56 mL/minute; 95% CI, -36.23 to -14.89 mL/minute), albuminuria, and systolic BP.

“In smaller, short-duration studies in patients with CKD, nonsurgical weight loss interventions reduce proteinuria and BP and seem to prevent further decline in renal function,” the review authors write. “In morbidly obese individuals with glomerular hyperfiltration, surgical interventions normalize GFR and reduce BP and microalbuminuria. Larger, long-term studies to analyze renal outcomes such as development of ESRD [end-stage renal disease] are needed.”

Limitations of this study include possible publication bias, suboptimal quality and short duration of the included studies, insufficient power to measure patient-centered outcomes such as mortality, and the presence of heterogeneity in the analysis.

“It seems that weight loss may offer renal benefits in addition to the cardiovascular benefits, thereby reducing both the cardiovascular and the CKD risks in these patients; however, the evidence supporting the role of intentional weight loss in patients with mild to moderate CKD to slow the progression of kidney disease is modest at best, and more research is needed in this area,” the review authors conclude.