# Cost of Serious Infections in Chronic Lymphocytic Leukemia

## TL;DR

This study estimates the high costs of serious infections in chronic lymphocytic leukemia patients in Australia, showing significant financial impacts on hospital care.

## Contribution

The paper provides new cost estimates for serious infections and related treatments in a large CLL cohort over six years.

## Key findings

- The mean inpatient cost per patient per month was AU$1291, peaking at AU$4168 in the month of CLL diagnosis.
- Serious infections added AU$22,905 in excess costs per patient in the month of occurrence, with elevated costs for six months afterward.
- IgRT and anticancer treatments cost AU$3288 and AU$5223 per patient per month, respectively.

## Abstract

The economic burden of chronic lymphocytic leukemia (CLL) is high, and is projected to increase with the introduction of new targeted treatments and improved survival. These high costs are not only associated with anticancer treatment, but also with the treatment and prevention of CLL symptoms and adverse events. Infections are among the most common adverse events in CLL patients, resulting from immune dysregulation caused by both the underlying disease and treatments. Immunoglobulin replacement therapy (IgRT) is one prophylactic measure used to prevent infections, but its effectiveness in CLL is unclear and costs are substantial. The aim of this paper was to estimate the excess cost associated with serious infections in patients with CLL, and explore other factors that may increase hospitalization costs in Australia.

We conducted a retrospective longitudinal study of linked hospital data, including 3705 patients with CLL and hospital admissions between July 2016 and June 2022. We estimated the excess cost associated with serious infections, inhospital anticancer treatment and IgRT using generalized linear models with gamma distribution and identity link.

Over the study period, the mean inhospital cost per patient per month was AU$1291 (US$892) and was highest in the month of CLL diagnosis, at AU$4168 (US$2880). The excess cost in the month of a serious infection was AU$22,905 (US$15,829) per patient, and costs remained higher in the subsequent 6 months. The monthly costs associated with IgRT and anticancer treatment were AU$3288 (US$2772) and AU$5223 (US$3609) per patient, respectively.

Our results highlight the high economic burden of serious infections in a large cohort of patients with CLL over a 6‐year period. Further costing studies including costs to the patient and healthcare utilization in the outpatient setting are needed to ascertain the total cost of infections and the overall cost of cancer care in patients with CLL.