Factors Affecting Discharge Dispositions in NF2 Patients Following Surgery for Acoustic Neuroma: A U.S. Nationwide Inpatient Data Sample Study (2005-2009)

Introduction: Patient outcome and hospitalization cost following acoustic neuroma surgery in patients with NF2 depend on several factors. The outcome and mortality can be affected by patient factors (comorbidity status, associated surgical complications), demographic-factors (age, sex, race), and hospital factors (teaching status, bed size, urban or rural location). The data in the available literature lack a detailed analysis of the pertinent variables that can impact the surgical outcome in acoustic neuroma patients with NF2. Similarly, the hospitalization cost of these patients can also be affected by various factors. The objective of the current study is to look at the factors that can affect the hospitalization cost, mortality, and discharge disposition of patients with NF2 who undergo surgery for acoustic neuroma.

Material and Methods: We analyzed the national estimates of NIS (Nationwide Inpatient Sample) database over the years 2005-2009 using discharge weights. The denominator of the study was NF2 patients who were surgically treated for acoustic neuromas. Patients with non-NF2 acoustic neuroma were selected as a reference cohort. Several variables were analyzed from the database including patient demographics, surgical complications, and comorbidities. A total of 30 comorbidities were analyzed and individual comorbidities in a patient were calculated. It ranged from 0 to a maximum of 12. Quartiles were used, and individuals above the 75th percentile formed the highest comorbidities index cohort and higher cost-incurred cohort. Hospital variables such as teaching status, bed size, and rural or urban location were also looked at. Patient outcome and increased hospitalization costs were the dependent variable studied. Univariate analysis was followed by multivariate-binary-logistic-regression analysis. Comparison of hospitalization costs was done by a nonparametric test of Kruskal-Wallis.

Results: A total of 399 admissions from 242 hospitals was analyzed from the NIS data over the years 2005-2009. The mean age was 29.39 years (SD, 14.52; range, 8-67 years), which was significantly (P < 0.000) less than the reference cohort .Only one patient was older than 65 years of age.

The cumulative cost incurred by the hospitals during the years 2005-2009 was $43.05 million. The mean expenditure per admission was $109,338.80 (SD, $100,363.32; range, $15,447 - $646,890). The mean total charges per admission rose from $83,125.00 in 2005 to $168,881.00 in 2009. The West region had significantly higher (P < 0.000) mean hospital charges compared with other regions. Patient factors like respiratory complication were strong independent predictors of increased hospital charges (P < 0.000;OR, 3.962; 95% CI, 1.811-8.662). Higher comorbidities (P = 0.016; OR, 1.043; 95% CI, 1.473-2.300) and West region (P < 0.000; OR, 5.766; 95% CI, 2.722-12.217) were associated with higher hospital charges. The majority of patients were treated in the West region (n = 224). The factors that predicted most significantly with worse outcome were high comorbidity index (P < 0.023;OR, 3.351; 95% CI, 1.184-9.482) and respiratory complication (P = 0.000; OR, 3.793; 95% CI, 1.782-8.075). The West region (P < 0.000; OR, 101; 95% CI, 0.041-0.245) and teaching status (P < 0.041; OR, 146; 95% CI, 0.512-0.566) of a hospital predicted negatively for worse outcome.

Conclusion: Our study has shown that several factors can affect patient outcome and hospital charges in patients with NF2 who have undergone surgery for acoustic neuroma. NF2 patients are younger and are treated preferentially at high volume in the West region, which has better outcomes but significantly higher cost. High comorbidities not only increases the hospitalization cost but also predisposes to worse outcome.