Underweight Is an Independent Risk Factor for Renal Function Deterioration in Patients with IgA Nephropathy

Abstract

Studies on the relationship between body mass index (BMI) and renal progression in IgA Nephropathy (IgAN) were limited, especially for underweight patients with IgAN. To elucidate the clinical features and effect of underweight on renal function deterioration in this disease, we recruited IgAN patients with diagnostic age ≥18 years old and a baseline estimated glomerular filtration rate (eGFR) ≥15 ml/min/1.73m2 from our center between 1985 and 2014. Patients secondary to systemic diseases or follow-up less than 6 months were excluded. All patients’ clinical data at renal biopsy and during follow-up were recorded. Renal outcome was defined as end-stage kidney disease (ESRD). Baseline body mass index (BMI) was calculated by weight (kg) over squared height (m2). According to WHO Asian guideline, BMI was categorized as follows: <18.5kg/m2 (underweight), 18.5–22.99kg/m2 (normal weight), 23–27.49kg/m2 (overweight) and obese (≥27.5 kg/m2). Of 930 primary IgAN patients enrolled in this study, mean age at renal biopsy was 37.6 years and 49.2% were men. Totally, 114 (12.3%) ESRD occurred after a mean follow-up of 47.1 months. More ESRD happened in underweight patients (17.3%) compared to patients with normal weight (13.2%), overweight (11.0%) or obesity (9.5%). By multivariate Cox regression analysis, underweight was independently associated with a higher risk of ESRD after adjustment for demographic characteristics and clinical variables (HR: 3.5, 95% CI: 1.3–9.5, P = 0.01) comparing to normal weight. Underweight patients had lower hemoglobin, serum uric acid, triglycerides, cholesterol and lymphocyte counts than patients with normal weight. Furthermore, BMI was positively correlated with serum C3 (r = 0.25, p <0.001). Our research finds that underweight is an independent risk factor for kidney disease progression in IgAN, which might be associated with malnutrition status and decreased C3 levels.

Uric Acid as a Predictor of Immunoglobulin A Nephropathy Progression: A Cohort Study of 1965 Cases

“…Recently, Matsukuma found a J-shaped association between SUA levels and poor renal survival in female patients with IgAN [21]. However, in Matsukuma's study [21], the female patients with the lowest SUA level presented with the lowest level of BMI, which may indicate malnutrition of these subjects that has been demonstrated as an independent risk factor for progression in IgAN [34,35]. In the present study, BMI level in the patients with the lowest quartile of SUA was not significantly lower than that in the patients of the other quartiles.…”

IgA Nephropathy Susceptibility Loci and Disease Progression

“…The high heterogeneity of prognosis in patients with IgA nephropathy brings difficulties to patient management and treatment. Risk factors were identified, including baseline kidney function, BP, proteinuria, serum albumin, hemoglobin, blood type, body weight, Oxford-MESTC score, and follow-up proteinuria and BP (13)(14)(15)(16)(17)(18)(19). To enhance the predicting accuracy, risk equations were established that showed better performance in predicting prognosis (12)(13)(14)(15)17,19,31).…”

“…The prognosis of IgA nephropathy is highly variable and it is challenging for clinicians to accurately predict kidney outcome at the time of biopsy. Studies on risk factors were carried out and risk models were established by combining independent clinical or pathologic risk factors together to enhance the predictable power of models (12)(13)(14)(15)(16)(17)(18)(19). Most recently, an extended multicenter study developed and validated two risk models by using clinical and Oxford predictors on the basis of Chinese patients with IgA nephropathy.…”

New strategies and perspectives on managing IgA nephropathy

“…Body mass index (BMI) at either extreme correlates with increased morbidity and mortality in CKD [ 23 – 25 ]. A Chinese case–control study demonstrated an association between low BMI (< 18.5 kg/m 2 ) and likelihood of end-stage renal disease (ESRD) in IgAN [ 26 ], and a similar Japanese study found patients with elevated BMIs (> 23 kg/m 2 ) had lower rates of proteinuria remission following treatment [ 27 ]. Obesity is postulated to increase proteinuria by inducing ultrastructural changes to the glomerular basement membrane [ 28 , 29 ].…”