638P Burden of infection in patients with multiple myeloma and secondary immunodeficiencies: A retrospective cohort study

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This study aimed to provide insights into the burden of infection in patients with multiple myeloma (MM) with or without secondary immunodeficiencies (SID). In this retrospective cohort study, data were extracted from the Optum-Humedica electronic record database during the period 01-Oct-2015 to 10-Mar-2020, which included a 6-month pre-index period (PIP) and 12-month follow-up following patient identification. Patients aged ≥18 years with a confirmed diagnosis of MM in the PIP were included in the analysis and stratified into two cohorts: those with (SID cohort) and those without SID (no-SID cohort). If a patient had SID or primary immunodeficiencies in the PIP, they were excluded. The first occurrence of a hypogammaglobulinemia ICD-10 code, or a low (<5.0 g/L) serum Immunoglobulin G level was defined as the SID index date. Of patients with MM, 870 with SID and 3768 without SID were included (mean age: 66.5 and 68.7 years; males: 54.3% and 53.6%; respectively). At 12-month follow-up, significantly more patients in the SID cohort experienced ≥1 infection than the no-SID cohort (58.9% vs 32.1%, p<0.001). A similar pattern was observed for mean number of infections, patients experiencing ≥1 severe bacterial infection or ≥1 infection-associated hospitalization (Table). The most common infection in both cohorts was bacterial: SID, mean (standard deviation [SD]) number of bacterial infections 6.83 (8.04) and no-SID, 4.73 (6.57), p<0.001. Kaplan–Meier analysis showed overall survival (OS) at 24 months was lower in the SID cohort (74.9% of patients alive) than the no-SID cohort (81.8%).Table: 638POutcome measures at 12 monthsSID n=870No-SID n=3768p value SID vs no-SIDNumber of infections, mean (SD)7.07 (9.23)4.58 (6.45)<0.001Patients with ≥1 severe bacterial infection,a n (%)276 (31.7)510 (13.5)<0.001Patients with ≥1 hospitalization associated with any infection, n (%)231 (26.6)350 (9.3)<0.001Number of hospitalizations, mean (SD)6.55 (8.65)5.47 (6.90)0.11Length of hospital stay, mean (SD), days13.02 (34.95)9.69 (26.88)0.22aDefined using ICD-10 codes for bacteremia or sepsis, bacterial meningitis, osteomyelitis/septic arthritis, bacterial pneumonia and visceral abscess. Open table in a new tab aDefined using ICD-10 codes for bacteremia or sepsis, bacterial meningitis, osteomyelitis/septic arthritis, bacterial pneumonia and visceral abscess. Patients with MM and SID have a substantially higher burden of infection and healthcare resource use, and lower OS than those without SID. Understanding this burden will allow for earlier targeted treatment of individuals at risk of SID. Study/medical writing support funder: Takeda Development Center Americas, Inc.