Racial and Health Insurance Disparities of Inpatient Spine Augmentation for Osteoporotic Vertebral Fractures from 2005 to 2010

Discussion

Our study demonstrated significant racial and health insurance–based disparities in the use of spinal augmentation for the treatment of osteoporotic vertebral fracture. Compared with white patients, all racial and ethnic minority groups had significantly lower rates of inpatient spine augmentation. Indeed, less than one-half of black patients admitted with a primary diagnosis of vertebral fracture were treated with spine augmentation, while nearly two-thirds of white patients underwent spine augmentation. Differences in spine augmentation use among Hispanic and Asian/Pacific Islander patients compared with white patients were also statistically significant, but the degree of difference was much less marked than that seen in black-versus-white patients. Conversely, when implemented, the type of augmentation used, either kypho- or vertebroplasty, was quite similar among racial groups. Despite the large sample size in our study, there is significant under-representation of patients who were not white as black patients composed only 2.7%, Hispanic patients composed 4.1%, and Asian/Pacific Islander patients composed 1.9% of the sample size. The reason for this difference is unclear and may be multifactorial, including lower fracture rates for black, Hispanic, and Asian women compared with white women⁸ and disparities in osteoporosis treatment in these minority groups.⁹

Similar to race, the insurance provider also had a profound impact on the use of spine augmentation, with patients with Medicare and private insurance having augmentation at markedly higher rates than either patients with Medicaid or those who self-paid. In our multivariate analysis, the differences noted above were as great or greater than those in the univariate analyses. Overall, these findings suggest that significant health insurance status disparities exist in the use of spine augmentation procedures, findings consistent with the already reported disparities in access to health care by minorities and the uninsured.^{5,10⇓⇓⇓⇓–15}

These current findings are potentially clinically relevant because prior studies have shown that patients receiving spine augmentation procedures demonstrate improved survival and quality of life compared with patients receiving nonoperative treatment.^16,17 In a study of the 2006 Medicare Provider Analysis and Review File data base, Chen et al¹⁶ demonstrated that patients who underwent vertebroplasty and kyphoplasty had significantly higher 3-year survival rates compared with patients receiving nonoperative management. The Fracture Reduction Evaluation study, which randomized patients into balloon kyphoplasty and nonsurgical management, demonstrated that kyphoplasty was associated with improved quality of life.¹⁷

While this study was not designed to determine the specific causes behind racial and insurance-based disparities, we believe that the causes of such disparities are multiple, including but not limited to physician bias, access to care, patient preferences, and communication barriers.^{18⇓⇓⇓⇓–23} While high costs of spine augmentation procedures could contribute to the lower rates of spine augmentation in some groups, our subgroup analysis of patients with Medicare demonstrated that racial minorities still had lower rates of spine augmentation despite having the same type of insurance as their white counterparts. Racial disparities in the care of patients with osteoporosis have been previously identified. In a study of patients with Medicare and osteoporotic fractures, Liu et al²⁴ demonstrated that black patients were significantly less likely to receive both prefracture and postfracture care compared with white patients. Yoo et al²⁵ demonstrated significant racial disparities in osteoporosis drug maintenance therapy between black and white patients, especially among patients with Medicare, among whom supplementary health insurance was not affordable.

Insurance-based disparities in spine augmentation use may, at least in part, be explained by costs. In general, Medicare provides higher reimbursement rates for all medical services compared with Medicaid. In 2013, the Medicaid-to-Medicare fee index was 0.66 across the entire United States.²⁶ The inability of patients who self-pay and those with Medicaid to pay for the costs associated with spine augmentation could contribute to their lower rate of spine augmentation use overall. Cost differences may also explain our finding that patients with Medicaid and those who self-pay had significantly lower usage rates of kyphoplasty compared with patients who were privately insured, because kyphoplasty has been reported to cost between 2 and 20 times more than vertebroplasty.^27,28 It is unclear to us as to why patients who were privately insured used spine augmentation less than those with Medicare in our study; one theory may be that there are preauthorization barriers that discourage the use of spine augmentation in this population.

Several prior studies have demonstrated disparities in the surgical treatment of back pain. Carey et al demonstrated that hospitalization and surgery rates were significantly lower in black patients with chronic back pain.²⁹ In a study of the Nationwide Inpatient Sample, Alosh et al³⁰ found that racial minorities were significantly less likely to receive cervical spine surgery for the treatment of degenerative cervical spine disease. The Alosh et al study also demonstrated that patients with Medicaid were significantly less likely to receive surgery compared with those with private insurance.³⁰ In a study of Workers' Compensation claims in Missouri, Chibnall et al³¹ found that white patients were significantly more likely to receive a diagnosis of a herniated disk and that among those with such a diagnosis, whites were significantly more likely to undergo surgery compared with black patients. These studies further support our findings that minorities and the underinsured are treated differently for spine disease.

There are several limitations to our study. Our use of broad racial designations (white, black, Hispanic, Asian/Pacific Islander) in an effort to maintain consistency within the NIS data base may have limited our sample population because some racial groups are heterogeneous. Despite our ability to demonstrate usage disparities, we did not analyze outcome data for these procedures and cannot comment on morbidity or postoperative functional status across groups. Our study only examined disparities among inpatients diagnosed with osteoporotic vertebral fractures. However, a prior study of Medicare enrollees found that only 40% of vertebroplasties between 2001 and 2005 were performed as inpatient procedures. In addition, while the NIS is a large inpatient data base, it does not include federally funded health care facilities. It is unclear to us as to why privately insured patients used spine augmentation less than Medicare patients in our study; one theory may be that there are preauthorization barriers that discourage the use of spine augmentation in this population. As with any analysis of a large data base, errors in coding are also a potential limitation,³² though error rates are likely similar between racial and insurance groups. Finally, given the very large size of the data base, numerous comparisons reach statistical significance yet have a very small, absolute difference; we have attempted throughout the article to highlight differences that may be clinically relevant.