The role of body mass index on IgA nephropathy prognosis: a systematic review and meta-analysis.

Background: Recent studies show that obese patients have worse outcomes in IgA nephropathy as compared to normal weight patients.

Materials And Methods: We performed a systematic review and meta-analysis of prospective, retrospective, randomized and nonrandomized studies, which studied the impact of obesity or high body mass index (BMI) on different parameters of IgA nephropathy prognosis and outcome. We searched through PubMed, Ovid/Medline, Web of Science, and the Cochrane Central Register of Controlled Trials (Wiley).

Results: We included 16 studies in our final analysis with a total of 4258 patients. Overall, there was a significantly lower estimated glomerular filtration rate (eGFR) in IgA nephropathy patients with BMI in the overweight/obese range than in those with normal BMI (mean difference 6.01, 95% CI 2.78-9.24 ml/min/1.73 m, P < 0.001), but no significant difference in serum creatinine or proteinuria levels. No studies measured GFR. There were contradictory results regarding the relationship between BMI and blood pressure, histological parameters or outcomes in patients with IgA nephropathy.

Conclusions: Higher BMI in IgA nephropathy patients might be associated with lower kidney function, but this should be confirmed by measuring GFR. Evidence regarding other kidney damage parameters and outcomes is inconclusive.