Predictors of Mortality and Readmission for Tumor Lysis Syndrome Hospitalizations in Lymphoid Malignancies

Introduction

The epidemiology of readmission following hospitalization for tumor lysis syndrome (TLS) in common lymphoid malignancies is not well known. In a cohort of patients with Non-Hodgkin's lymphomas (NHL) and multiple myelomas (MM), we sought to characterize risk factors for mortality and 90-day readmissions following an initial TLS episode using the 2019 Nationwide Readmissions Database (NRD).

Methods

The NRD is a nationally weighted database which captures approximately 60% of all hospitalizations in the United States. Patients were identified using international classification of diseases 10 coding (ICD 10), and those with Hodgkin lymphomas or multiple malignancies were excluded. Variables included were patient demographics, comorbidities, complications of TLS during index hospitalization, frailty as defined by the hospital frailty risk score, and facility factors. Outcomes assessed included 90-day readmission and mortality. Risk factors were evaluated by univariate and multivariate analyses.

Results

1,840 patients were hospitalized for TLS between January and September 2019. 1,393 (76%) had NHL and 447 (24%) had MM. 1,001 (53%) patients were aged 65 years and above, and 1,429 (77%) were defined as frail. The median length of stay for an index TLS admission was 9.5 (IQR 4.6-17.2) days. 351 (19%) of patients died during index visit. On multivariate analysis, factors associated with mortality included respiratory arrest (OR 4.62; 95% CI 3.35-6.37), frailty (OR 3.07, 95% CI 1.73-5.44), sepsis (OR 2.45; 95% CI 1.78-3.39), arrythmia (OR 1.91; 95% CI 1.40-2.77), and acute kidney injury (OR 1.56; 85% CI 1.15-2.12). Increased index admission cost > 75^th percentile was associated with decreased mortality (OR 0.67, 95% CI 0.47-0.94). Of 1,489 patients discharged alive from the index TLS admission, 586 (40%) were readmitted within 90-days. The mean cost of a readmission episode was $26,247 (SE $2,835). The most common cause of readmission was sepsis accounting for 72 out of 586 (12%) readmissions. Discharge to home vs facility (OR 1.78; 95% CI 1.36-2.32), fluid overload during index admission (OR 1.74; 95% CI 1.27-2.40), large hospital vs small hospital based upon number of beds (OR 1.73; 95% CI 1.19-2.49), medium hospital vs small hospital based upon number of beds (OR 1.65; 95% CI 1.07-2.55), and previous history of lymphoma (OR 1.31; 95% CI 1.06-1.62) were all associated with increased odds of 90-day readmission. Acute kidney injury during index TLS admission (OR 0.72; 95% CI 0.54-0.96) and current multiple myeloma (OR 0.50; 95% CI 0.38-0.67) were associated with decreased odds of readmission.

Conclusions

TLS is an important complication after diagnosis and during treatment of lymphoid malignancies, leading to both morbidity and mortality. Readmission after TLS diagnosis is a costly burden on patients and healthcare systems. Hospitals with a smaller bed-size had lower odds of 90-day readmissions compared to hospitals with medium and large bed-sizes. Patients that discharged home had higher odds of readmission compared to patients discharging to a facility. Previous history of lymphoma increased odds of 90-day readmission, while active diagnosis of multiple myeloma decreased odds of readmission. While acute kidney injury during index admission had decreased odds of readmission, it conferred increased odds of mortality. Identification of patient-based factors, facility based factors, and index complications that increase mortality and readmission risk may improve management of patients with TLS and lymphoid malignancies.

No relevant conflicts of interest to declare.