Predictors of in-Hospital Mortality in Patients with Primary Central Nervous System Lymphoma

INTRODUCTION

Primary central nervous system lymphoma (PCNSL) is a variant of Non Hodgkin’s lymphoma (NHL) arising in the cranio-spinal axis without evidence of systemic involvement. The estimated age adjusted incidence of PCNSL is 0.48 per 100,000. Although uncommon, PCNSL is associated with significant morbidity and mortality. The aim of our study is to better describe the factors affecting the in hospital course and mortality in patients with PCNSL.

METHODS:

We queried the Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample (NIS) between 2007 and 2011 using the ICD-9 diagnosis code. We separated hospitalizations with diagnosis of PCNSL (ICD 9 - 200.5). Severity of co-morbidities was determined using Deyo modification of Charlson’s co-morbidity index (CCI). Primary outcome of the study was in-hospital mortality and secondary outcomes were length of stay (LOS) and cost of care. The cost of care was adjusted for inflation using Consumer Price Index (CPI) published by Bureau of Labor Statistics. Multivariate predictors for in-hospital mortality were identified by logistic regression model and multivariate predictors for LOS and cost of care were identified by linear regression model. Using SAS 9.2, survey procedures were used to accommodate for hierarchical two-stage cluster design of NIS.

RESULTS

A total of 3,391 hospitalizations (weighted N =16,790) with primary CNS lymphoma were available for analysis. After controlling for potential confounding factors (age, sex, human immunodeficiency virus [HIV] infection, Epstein -Barr virus infection, rheumatoid arthritis, diffuse diseases of connective tissue, myasthenia gravis, sarcoidosis, systemic vasculitis, organ transplantation, immune deficiency syndromes, charlson's index, hospital region in the United States, teaching status of the hospital) immunodeficiency syndromes (Odds ratio [OR] 16.532 95% CI 1.802-151.706), HIV infection (OR 4.762 95% CI 1.110-20.434), African American(AA) Race (OR 2.869 95% CI 1.075-7.659) and increasing age (OR 1.030, 95% CI 1.001-1.059) were found to be independent predictors of increased mortality in patients with PCNSL.

Charlson’s index (OR 1.034 95% CI 0.856-1.250), history of organ transplantation (OR 0.658 95% CI 0.066-6.521), female gender (OR 0.668 95% CI 0376-1.189) and teaching status of the hospital (OR 0.542 95% CI 0.258-1.139) were not associated with increased mortality. There was no difference in mortality and length of hospital stay amongst the hospitals in different geographical regions. The teaching status of the hospital was not associated with in-hospital mortality, but was found to be associated with an increased average LOS (0.644161 days more, p value=0.0006) and cost of hospitalization (4498.4 dollars more per hospitalization, p value <0.0001).

In addition to AA race being an independent predictor of mortality, the average length of hospital stay in AA population was 2.2 days higher (p= 0.0003) than the Caucasian population and was also associated with a higher average cost of hospitalization (4777.2 dollars more per hospitalization, p< 0.0001). In sub analysis for racial predisposition on mortality in HIV- PCNSL patients we found that presence of infection was associated with increased risk of mortality in Caucasian population however there was no risk increase noted in the AA population. (p =0.0003).

CONCLUSIONS

Our analysis revealed that immunodeficiency syndromes, HIV infection, AA race and increasing age were independent predictors of in hospital mortality in PCNSL patients. History of organ transplantation, associated co morbidities (charlson’s index), female gender and teaching status of the admitting hospital were not associated with increased mortality. Interestingly, HIV infection was a risk factor in Caucasians but not in African Americans.