Overall Survival (OS) of Acute Myeloid Leukemia (AML) Treated at Academic Center (AC) Versus Non-Academic Center (NAC)

Introduction:

Prior studies in cancer have suggested better OS of patients treated at AC as compared to NAC. This may be related to the availability of physicians with expertise in specific malignancies, better multidisciplinary care and access to more resources and clinical trials. Whether academic status of the facility affects OS of AML is unknown.

Methods:

We utilized the National Cancer Database Participant User File (NCDB PUF) to extract patient-level data of patients with AML reported between 1998 to 2011. Hospital facilities were classified as either AC (academic/research program) or NAC (community cancer program, comprehensive community cancer program, and other, per NCDB classification).We included only those patients, who had all of the first course treatment or a decision not to treat made at the reporting facility. Subjects with complete and known data for the variables sex, age, race, education, income, distance traveled for health care, hospital type, facility location, urban/rural location, insurance, Charlson co-morbidity score, chemotherapy use, time from diagnosis to treatment initiation, use of hematopoietic stem cell transplant, 30-day mortality, last contact, and vital status were included. These variables were analyzed in a univariate analysis. Kaplan Meier curves were drawn and compared using log rank test. Multivariate analysis was done using logistic regression for 30-day mortality and Cox regression with backward elimination approach for OS. Statistical analysis was done using PC SAS version 9.4.

Results:

A total of 7823 AML patients were studied, of which 4681 (60%) patients received treatment at AC. Patients treated at AC differed from NAC in the median age (62 vs. 67years; p <0.001), race (p <0.001), education (p=0.005), income (p <0.001), co-morbidity score (p=0.019), insurance (p<0.001), receipt of chemotherapy (p<0.001), transplant (p<0.001) and facility location (p<0.001). The median OS (12.6 vs. 7.0 months; p value <0.001) and 1-year OS (51% vs. 39%; p value <0.001) was better in AC as compared to NAC. In a multivariate analysis, the 30-day mortality was significantly worse in NAC as compared to AC (odds ratio, OR 1.52; 95% confidence interval, CI 1.33-1.74; p <0.001) (Table 1). Similarly, Cox regression showed that the OS was significantly worse in NAC as compared to AC (hazard ratio, HR 1.13; 95% CI 1.07-1.19; p <0.001) after adjusting for age, sex, Charlson co-morbidity score, receipt of chemotherapy, transplant, insurance and income status and facility location. 

Conclusion:

Our population-based study suggests that the receipt of initial therapy at AC versus NAC is associated with lower 30-day mortality and higher 1-year OS. This may presumably be related to the provision of dedicated multidisciplinary leukemia teams, access to more resources and clinical trials in AC. The reasons behind such differences should be investigated in future studies, and necessary steps be taken to minimize this gap.

Table 1: Multivariate logistic regression of 30-day mortality

Variable	Odds ratio	95% confidence interval	P value
Academic (ref) Non-Academic	1 1.52	1.33-1..74	<0.001
Age  - <60 years (ref) - > 60 years	1 2.32	1.92-2.80	<0.001
Charlsonco-morbidity score  -0 (ref)  -1 - 2 or more	1 1.45 2.14	1.23-1.69 1.74-2.63	<0.001 <0.001
Chemotherapy  - Yes (ref)  - No	1 2.55	1.93-3.38	<0.001
Days until first treatment	0.87	0.86-0.89	<0.001
Income status  - $ 46,000 + (ref)  - < $ 30,000  - 30,000-34,999  - 35,000-45,999	1 1.31 1.31 1.21	1.06-1.62 1.09-1.58 1.03-1.43	0.011 0.004 0.023
Insurance Status  - Private insurance/managed care (ref) - Not insured - Medicaid - Medicare - Other government	1 2.32 0.81 1.56 1.13	1.66-3.24 0.59-1.10 1.30-1.87 0.63-2.02	<0.001 0.178 <0.001 0.686

 

Figure 1: Kaplan Meier curve showing cumulative survival among AML patients treated at academic versus non-academic centers (p value of log rank test <0.001)