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.

Incidence of Skin and Respiratory Immune-Related Adverse Events Correlates With Specific Tumor Types in Patients Treated With Checkpoint Inhibitors

Checkpoint inhibitors (CPIs) increase antitumor activity by unblocking regulators of the immune response. This action can provoke a wide range of immunologic and inflammatory side effects, some of which can be fatal. Recent studies suggest that CPI-induced immune-related adverse events (irAEs) may predict survival and response. However, little is known about the mechanisms of this association. This study was undertaken to evaluate the influence of tumor diagnosis and preexisting clinical factors on the types of irAEs experienced by cancer patients treated with CPIs. The correlation between irAEs and overall survival (OS) was also assessed. All cancer patients treated with atezolizumab (ATEZO), ipilimumab (IPI), nivolumab (NIVO), or pembrolizumab (PEMBRO) at Virginia Mason Medical Center between 2011 and 2019 were evaluated. irAEs were graded according to the Common Terminology Criteria for Adverse Events (Version 5) and verified independently. Statistical analyses were performed to assess associations between irAEs, pre-treatment factors, and OS. Of the 288 patients evaluated, 59% developed irAEs of any grade, and 19% developed irAEs of grade 3 or 4. A time-dependent survival analysis demonstrated a clear association between the occurrence of irAEs and OS (P < 0.001). A 6-week landmark analysis adjusted for body mass index confirmed an association between irAEs and OS in non-Small Cell Lung Cancer (NSCLC) (P < 0.03). An association between melanoma and skin irAEs (P < 0.01) and between NSCLC and respiratory irAEs (P = 0.03) was observed, independent of CPI administered. Patients with preexisting autoimmune disease experienced a higher incidence of severe irAEs (P = 0.01), but not a higher overall incidence of irAEs (P = 0.6). A significant association between irAEs and OS was observed in this diverse patient population. No correlation was observed between preexisting comorbid conditions and the type of irAE observed. However, a correlation between skin-related irAEs and melanoma and between respiratory irAEs and NSCLC was observed, suggesting that many irAEs are driven by a specific response to the primary tumor. In patients with NSCLC, the respiratory irAEs were associated with a survival benefit.