#3709 KIDNEY IMPAIRMENT AT DIAGNOSIS IN MULTIPLE MYELOMA: THE NEPHROLOGIST PERSPECTIVE

Abstract Background and Aims Kidney impairment (KI) at multiple myeloma (MM) diagnosis ranges between 20 and 50% and is associated with high mortality. Therefore, an important percentage of the newly diagnosed cases of MM come from nephrologists. We aimed to evaluate the new cases of MM with KI diagnosed in our nephrology tertiary care center for presentation features, initial treatment, and survival. Method We performed a unicentric retrospective study on 89 consecutive patients newly diagnosed with MM (median age 66 years, 38% male) between 2015-2020. Patients were followed until death or end of study (September 2022), whichever came first. Results The most common MM type was free light chain (FLC) only (55%) followed by IgG (30%), IgA (14%) and IgM (1%). Kappa FLC was more frequent than lambda FLC (53 vs 47%); the median FLC level was 1760 (IQR 450, 7373) mg/L, and the median marrow plasmocytosis was 30 (IQR 15, 60) %. Among the 89 patients, 81% presented with acute kidney injury, 12% with chronic kidney disease, 5% with isolated proteinuia and 2% with nephrotic syndrome. Baseline median serum creatinine and eGFR were 5 mg/dL and 9 mL/min, respectively. Median proteinuria was 3.3 (IQR 1.3, 6) g/g with median albuminuria of 0.27 (IQR 0.11, 0.66) g/g. More than one third (34%) of the studied patients needed hemodialysis (HD) at diagnosis, and 50% progressed to renal replacement therapy by the end of the follow up period (CKD5D). The most frequent clinical features at presentation were asthenia (75%), followed by bone pain (51%), orthostatic hypotension (14%), peripheral neuropathy (10%), edema (10%) and dyspnea (6%). Arterial hypertension (71%), systemic atherosclerosis (58%), ischemic heart disease (44%) and diabetes mellitus (12%) were the most frequent recorded comorbidities. Treatment with dexamethasone was started by the nephrologist in 74% of the patients at a median dose of 128 (IQR 96, 160) mg, afterwards the patients were reffered to hematology for a bortezomib based regime. During the follow up period 58 (65%) patients died; they had higher serum creatinine (5.8 vs 2.5 mg/dL, p 0.02), needed HD at diagnosis more often (41 vs 20%, p 0.01), had lower serum albumin (3.7 vs 4.4 g/dL, p 0.001), higher LDH (236 vs 201 U/L, p 0.01) and increased inflammation (C-reactive protein: 14 vs 3 mg/L, p 0.001). In univariate logistic regression, the risk factors at diagnosis associated with mortality were increased age (OR 1.07, 95%CI1.03-1.12), atherosclerotic burden (OR 5.51, 95%CI 2.13-14.22), low serum albumin (OR 0.28, 95%CI 0.13-0.63), inflammation (OR 1.05, 95%CI 1.01-1.09), increased LDH (OR 1.01, 95%CI 1.00-1.02) and the need for HD at diagnosis (OR 2.94, 95%CI 1.04-8.26). However, in multivariate analysis only low serum albumin (OR 0.22, 95%CI 0.05-0.90) and the need for HD at diagnosis (OR 10.64, 95%CI 1.71-66.14) were significantly associated with mortality. Conclusion Patients with MM and kidney impairment at diagnosis are more frequent kappa FLC, present most often as AKI, around one third of them require HD at diagnosis, and half of them progress to CKD5D. Therefore, these patients are a distinct group of MM with a high mortality rate (>60% at five years) who need interdisciplinary care.