Clinicopathological features and outcomes of patients with monoclonal immunoglobulinemia complicated with renal damage

Objective  To explore the clinicopathological features and outcomes of patients with monoclonal immunoglobulinemia complicated with renal damage.

Methods  From January 2017 to June 2019, 98 hospitalized patients of monoclonal immunoglobulinemia complicated with renal damage were recruited as research subjects. According to clinical manifestations and renal pathological changes, they were assigned into two groups of monoclonal gammopathy （MGRS） and multiple myeloma （MM）. Clinicopathological characteristics, creatinine free doubling survival and overall survival （OS） were compared between two groups. Cox regression analysis was utilized for obtaining independent predictors of creatinine free doubling survival and OS post-treatment.

Results  24-hour urinary protein （4.5 ± 1.1）g vs （3.7 ± 1.1） g, t/χ²=2.456, P=0.024, estimated glomerular filtration rate （eGFR）（49.2 ± 8.9）mL·min⁻¹·（1.73 m²）⁻¹ vs （37.6 ± 7.4） mL·min⁻¹·（1.73 m²）⁻¹, t/χ²=8.992, P＜0.001, hemoglobin （74.2 ± 4.8） g/L vs （63.5 ± 6.3） g/L, t/χ²=5.689, P＜0.001, proportion of nephrotic syndrome （89.1% vs 42.3%, t/χ²=8.896, P＜0.001） and proportion of light chain renal amyloidosis （82.6% vs 38.5%, t/χ²=9.323, P＜0.001） were significantly higher in MGRS group than those in MM group while proportion of males （80.8% vs 54.3%, t/χ²=4.532, P=0.030）, serum creatinine （232.4 ± 34.5） μmol/Lvs （183.2 ± 28.9） μmol/L, t/χ²=5.566, P＜0.001, albumin （26.8 ± 3.7） g/L vs （20.2 ± 4.0） g/L, t/χ²=3.756, P＜0.001 and light chain tubular nephropathy （57.7% vs 10.9%, t/χ²=9.323, P＜0.001） were significantly higher in MM group than those in MGRS group. And 1/2/3-year cumulative creatinine free doubling survival （93.6%, 86.7%, 74.3% vs 77.2%, 52.4%, 42.4%, χ²=4.893, P=0.27） and OS （100%, 89.4%, 77.5% vs 78.6%, 59.1%, 57.7%, χ²=5.113, P=0.22） were significantly higher in MGRS group than those in MM group. Multifactor Cox regression analysis indicated that eGFR was an independent predictor of creatinine free doubling event survival of MGRS patients. And eGFR and albumin were independent predictors of total survival of MGRS patients （P＜0.05）; eGFR and ISS stage were independent predictors of creatinine free doubling event survival. And eGFR, ISS stage and EGOC score were independent predictors of OS （P＜0.05）.

Conclusion  Great differences exist in clinical manifestations and survivals of MGRS/MM patients. MGRS has a better prognosis with higher rates of creatinine free doubling survival and OS. eGFR and albumin are independent prognostic factors of MGRS. And eGFR, ISS stage and EGOC score are independent prognostic factors of MM.