Among the 236,270 hospitalizations involving CAR-T approved cancer subtypes (DLBCL, multiple myeloma, follicular lymphoma, mantle cell lymphoma, and acute lymphoblastic leukemia), 1,030 (0.44%) hospitalizations involved administration of CAR-T between January 1, 2017, and December 31, 2020 (Figure 1, Supplementary Table 2). These 1030 unweighted hospitalizations represented approximately 4670 records after applying weights for national estimates. CAR-T hospitalizations steadily rose from 2017-2020 (Figure 2, Supplementary Table 2). DLBCL accounted for 70% of patients receiving CAR-T.
Among the 1030 unweighted hospitalizations, 43 records were missing race, 45 records were missing income quartiles, and 8 records were missing insurance status. (Multiple imputations were not indicated per the statistical plan, as the total records with missing variables were less than ten percent.)
Of the 1030 patients receiving CAR-T (mean age 55.6±18.1 years), 97 (9.4%) had an associated diagnosis of AF during their hospitalization. Compared to CAR-T patients without AF, those with AF were found to be older (mean age 68 vs. 54 years, p<0.001), more likely to be male (42% vs. 22%, p<0.001), more likely to be Caucasian (84% vs. 70%, p<0.001), have Medicare (57% vs. 30%, p<0.001), and have a higher prevalence of 3 or more comorbidities (59% vs. 38%, p<0.001) (Table 1).
Compared to the CAR-T without AF, CAR-T with AF was associated with higher prevalence of hypertension (56.7% vs 36.6%, p<0.001), hypotension (35% vs 28%, p=0.157), chronic heart failure (24.7% vs 7%, p<0.001), and coronary artery disease (18.6% vs 5%, p<0.001) as shown in Table 2. The prevalence of supraventricular arrhythmia, acute heart failure, pulmonary edema, acute myocardial infarction, gastrointestinal bleed, and disseminated intravascular coagulation were also more common in the CAR-T with AF group compared to CART without AF group. However, we were unable to report the number and percentages in these variables due to low frequencies. In the table, frequencies less than 11 are not specifically reported as per the data reporting and publishing policy of HCUP.(6, 12)
Univariable logistic regression models assessed the associations of in-hospital mortality in CAR-T admissions with age, sex, atrial fibrillation, race, hospital region, hospital bed size, household income, year, Charlson comorbidity, and insurance status (Table 3). Atrial fibrillation and Charlson comorbidity index were both associated with increased in-hospital mortality. A multivariable model (Table 3) analyzed the independent association of AF with hospitalization after adjusting for age, sex, race, household income, and Charlson comorbidity (included in the model given univariable p-values were £ 0.20). The adjusted odds of in-hospital mortality (the primary outcome) were more than three times higher in the group of CAR-T recipients with AF compared to the CAR-T group without AF (aOR: 3.87, 95% CI: 1.61, 9.30, p=0.003) (Tables 3 and 4).
Similar multivariable regression models were used for the secondary outcomes with the exception of length of stay, which was evaluated with negative binomial regression. The adjusted odds of pulmonary edema were more than three times higher (aOR: 3.29, 95% CI: 1.34, 8.09, p=0.010), adjusted odds of gastrointestinal bleed were more than five times higher (aOR: 5.46, 95% CI: 1.95, 15.29, p=0.001), and adjusted odds of acute heart failure more than ten times higher (aOR: 10.20, 95% CI: 2.15, 47.95, p=0.003) in CAR-T with AF compared to CAR-T without AF (Table 4). Length of stay was longer in CAR-T with AF versus without AF (mean length of stay 20.5 days vs 7.5 days, p<0.001, adjusted beta co-efficient 0.18, 95% CI: 0.01, 0.36, p=0.045) as also shown in Table 4.
The demographics, cancer types and in-hospital CV and bleeding diagnosis associated with CAR-T vs non-CAR-T in the five FDA approved cancer types are reported for reference. Only descriptive statistics are used given the potential differences in hospitalization indications in patients not receiving CAR-T. Among the 236,270 hospitalizations with cancer subtypes where CAR-T is approved, only 0.4% of hospitalization included the administration of CAR-T. The majority of CAR-T admissions were in patients with DLBCL (70.2%) followed by acute lymphoblastic leukemia (12.3%), multiple myeloma (11.6%) and mantle cell lymphoma (2.2%). (Supplementary Table 4).
Compared to patients not receiving CAR-T, patients receiving CAR-T had numerically higher incidence of hypotension (28.6% vs. 8.1%), ventricular tachycardia (3.2% vs. 1.5%), supraventricular tachycardia (3.4% vs. 1.8%), pulmonary edema (3.2% vs. 1.1%), mechanical ventilation requirement (4.4% vs 2.8%) and disseminated intravascular coagulation (3.7% vs. 2.4%). (Supplementary Table 4).
Since the ICD 10 diagnostic code for CRS was implemented in October, 2020, CRS could only be assessed after this date. CRS was diagnosed in 141 patients in the study cohort.(16) Among them, 21 patients (0.05%) developed CRS in the AF group compared to 120 patients (0.06%) who developed CRS in the non-AF group, p=0.733.
Given the potential impact of cancer type on outcomes, we performed a sensitivity analysis of our AF and CAR-T limited to patients with DLBCL alone, who constituted 70% of CAR-T patients. In a multivariable logistic regression model in the subgroup of DLBCL patients, the results were similar to the entire cohort. The odds of in-hospital mortality (the primary outcome), when adjusted for age, race, sex, Charlson comorbidity, and income were more than five times higher in CAR-T-cell with AF compared to CAR-T without AF (aOR: 5.84, 95% CI: 2.36, 14.47, p<0.001) (Supplementary Table 5). Similarly, the adjusted odds of pulmonary edema were more than two times higher (aOR: 2.73, 95% CI: 0.79, 9.36, p=0.111), the adjusted odds of gastrointestinal bleed were more than four times higher (aOR: 4.87, 95% CI: 1.13, 21.04, p=0.034), and the adjusted odds of acute heart failure more than seven times higher (aOR: 7.99, 95% CI: 1.54, 41.40, p=0.013) in CAR-T with AF compared to CAR-T without AF. While there was a similar trend in length of stay in the CAR-T with AF group compared to CAR-T without AF, the results were not significant (adjusted beta co-efficient 0.15, 95% CI: -0.06, 0.35, p=0.157; Supplementary Table 5).