The Impact of Adverse Events on Health Care Resource Utilization, Costs, and Mortality Among Patients Treated with Immune Checkpoint Inhibitors

BACKGROUND

We investigated the association between adverse events (AEs) suspected to be immune-related and health care resource utilization, costs, and mortality among patients receiving programmed cell death 1/programmed cell death ligand 1 immune checkpoint inhibitor (ICI) monotherapy for urothelial carcinoma, renal cell carcinoma, non-small cell lung cancer, or Merkel cell carcinoma.

PATIENTS AND METHODS

We conducted a retrospective cohort study using medical and pharmacy claims and enrollment information from U.S. commercial and Medicare Advantage with Part D enrollees in the Optum Research Database from March 1, 2014, through April 30, 2019. Claims were linked with mortality data from the Social Security Death Index and the National Death Index. Eligible patients had at least one ICI claim between September 1, 2014, and April 30, 2019.

RESULTS

After adjusting for potential confounding variables, we found patients with AEs had more than double the risk of an inpatient stay (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.9-2.5) and an 80% higher risk of an emergency visit (HR, 1.8; 95% CI, 1.6-2.1) than patients without AEs. Adjusted 6-month total costs were $24,301 higher among patients with an AE versus those without ($99,037 vs. $74,736; 95% CI, $18,828-29,774; p < .001). Mean ± SD AE-related medical costs averaged $2,359 ± $7,496 per patient per month, driven by inpatient visits, which accounted for 89.9% of AE-related costs. Adjusted risk of mortality was similar in patients with and without AEs.

CONCLUSION

Patients with AEs had higher risks of hospitalizations, emergency room visits, and higher health care costs, driven by inpatient stays, than patients without AEs. The adjusted risk of mortality was similar between the two cohorts.

IMPLICATIONS FOR PRACTICE

Patients taking immune checkpoint inhibitors (ICIs) who had adverse events (AEs) had significantly higher health care costs and utilization, driven by inpatient stays, compared with patients who did not. Given this high cost associated with AEs and the differences in the side effect profile of ICIs versus traditional chemotherapy, it is important for physicians to be cognizant of these differences when treating patients with ICIs. Ongoing evaluation, earlier recognition, and more effective, multidisciplinary management of AEs may improve patient outcomes and reduce the need for costly inpatient stays.

Immune-related adverse events and anti-tumor efficacy of immune checkpoint inhibitors

Although immune checkpoint inhibitors (ICIs) have transformed the treatment landscape for patients with many advanced malignancies, only 15-60% of patients respond, leaving a broad swath of patients who do not derive benefit. Identifying biomarkers to optimally identify patients who will benefit from ICIs is a major research focus for the oncology community. Thus far, predictive biomarker research has focused on tumor signatures such as microsatellite instability, programmed death-ligand 1 (PD-L1) expression and tumor mutational burden; clinical biomarkers have been far less studied. One potential clinical biomarker for ICI response in patients is immune-related adverse event (IRAE) onset.IRAEs are thought to represent bystander effects from activated T-cells and it is plausible that patients responding to ICIs would have greater likelihood of autoimmune toxicities (e.g. due to a more competent/treatment-responsive immune system, or cross-reactivity between tumor and host tissue). Earlier studies in melanoma patients however, suggested no association between IRAE onset and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody efficacy. In contrast, a growing body of literature suggests IRAE onset is predictive of anti-programmed cell death protein 1 (PD-1) and anti-PD-L1 antibody response across a variety of solid tumors. Most of these studies report that patients who experienced IRAEs demonstrate marked improvements in progression-free survival, overall survival and overall response rate compared to those lacking toxicity.Key questions regarding the association between IRAE onset and ICI efficacy remain. The most pertinent of these involve whether the association is only relevant for patients treated with anti-PD-1 and anti-PD-L1 antibodies and whether IRAE site, severity, timing of onset and management influence ICI efficacy. Herein, we discuss the seminal studies which have begun to address these questions and have shaped the narrative about the predictive value of IRAE onset for patients on ICIs, in this review.