Impact of body mass index on primary immunoglobulin A nephropathy prognosis: a systematic review and meta-analysis

Purpose The impacts of body mass index (BMI) on the prognosis of primary IgA nephropathy (IgAN) remain controversial. This systematic review and meta-analysis aimed to solve these issues. Methods We searched the PubMed, EMBASE, and Cochrane Library to screen articles investigating the BMI and primary IgAN. BMI was classified according to the World Health Organization as high (≥ 25.0 kg/m 2 ) and low (< 25.0 kg/m 2 ). The baseline renal indexes and the incidences of adverse renal outcomes were focused on. Results Six studies with a total of 1723 patients were included in this study. High BMI was demonstrated to be associated with increased baseline levels of serum creatinine (weighted mean difference (WMD) 9.54, 95% confidence interval (CI) 0.63–18.45), blood uric acid (WMD 19.85, 95% CI 10.11–29.59) and urine protein (WMD 0.37, 95% CI 0.21–0.53). Patients with high BMI also showed compromised eGFR at diagnosis (WMD − 8.39, 95% CI − 11.62 to − 5.16) with a higher incidence rate of hypertension (odds ratios (OR) 2.59, 95% CI 1.44–4.66) and higher global optical scores (WMD 1.22, 95% CI 0.70–1.74). Regarding the prognosis, high BMI was significantly associated with the incidence of adverse renal outcomes (OR 2.43, 95% CI 1.66–3.55, P < 0.001) and deteriorated eGFR at the last follow-up (WMD − 11.10, 95% CI − 16.96 to − 5.25, P < 0.001), with non-significantly poorer renal disease-free survival (hazard ratio 1.79, 95% CI 0.58–5.50, P = 0.31). Conclusion High BMI was associated with severe onset and poor prognosis of primary IgAN. The management of BMI could be a novel method to promote the therapeutic outcomes of primary IgAN.