Postoperative mortality after surgery for brain tumors by patient insurance status in the United States

Abstract

Objective: To examine whether being uninsured is associated with higher in-hospital postoperative mortality when undergoing surgery in the United States for a brain tumor.

Design: Retrospective cohort study using the Nationwide Inpatient Sample, January 1, 1999, through December 31, 2008.

Setting: The Nationwide Inpatient Sample contains all inpatient records from a stratified sample of 20% of hospitals in 37 states.

Patients: A total of 28,581 patients, aged 18 to 65 years, who underwent craniotomy for a brain tumor. Three groups were studied: Medicaid recipients and privately insured and uninsured patients.

Main outcome measure: The main outcome measure was in-hospital postoperative death. Associations between this outcome and insurance status were examined within the full cohort and within the subset of patients with no comorbidity using Cox proportional hazards models. These models were stratified by hospital to control for any clustering effects that could arise from differing access to care.

Results: In the unadjusted analysis, the mortality rate for privately insured patients was 1.3% (95% CI, 1.1%-1.4%) compared with 2.6% for uninsured patients (95% CI, 1.9%-3.3%; P < .001) and 2.3% for Medicaid recipients (95% CI, 1.8%-2.8%; P < .001). After adjusting for patient characteristics and stratifying by hospital in patients with no comorbidity, uninsured patients still had a higher risk of experiencing in-hospital death (hazard ratio, 2.62; 95% CI, 1.11-6.14; P = .03) compared with privately insured patients. In this adjusted analysis, the disparity was not conclusively present in Medicaid recipients (hazard ratio, 2.03; 95% CI, 0.97-4.23; P = .06).

Conclusions: Uninsured patients who underwent craniotomy for a brain tumor experienced the highest in-hospital mortality. Differences in overall health do not fully account for this disparity.

Figure 1

A: Derivation of the final study cohort. A total of 78,210,598 patient records were available in the NIS database from 1999-2008. Of these, 28,581 patients underwent a craniotomy for a brain tumor; were ages 18-65; had either private insurance, Medicaid, or no insurance; and had no missing data. B: For the subset analysis of patients with no major medical co-morbidity, a total of 17,892 records were excluded due to the presence of a co-morbidity, or missing co-morbidity data, leaving 10,689 patients with no major co-morbid condition.

Figure 2

By selecting for patients with no co-morbidity, there is minimal inadvertent selection for other characteristics. Patients with no co-morbidity have similar baseline characteristics compared to all neurosurgical patients. The main exception was age, which was about 5 years younger in patients with no co-morbidity compared to the full patient cohort, and was among the variables adjusted for in the final analysis.