Racial/ethnic and income-based differences in the use of surgery for cervical and lumbar disorders in New York State: a retrospective analysis.

BACKGROUND CONTEXT

The extent to which use of spine surgeries for patients with cervical and lumbar disorders varies by their race/ethnicity and income is currently unknown.

PURPOSE

To assess racial/ethnic and income-based differences in use of spine surgery in New York State (NYS) from 2016 to 2019.

STUDY DESIGN

Retrospective observational analysis using 2016 to 2019 New York Statewide Planning and Research Cooperative System (SPARCS) data, direct standardization, and multivariable mixed-effects linear regression models.

METHODS

A dataset of patients who underwent surgery for cervical and spinal disorders in NYS in the period 2016 to 2019 was used to determine county-level age- and sex-standardized annual cervical and lumbar surgery rates expressed as number of surgeries per 10,000 individuals. Further sub-analysis was performed with the key independent variables being the combination of individual-level race/ethnicity (Nonhispanic White, Nonhispanic Black, and Hispanic individuals) and income (low-/high-income residing in zip codes below/above state median income); and year. We estimated multivariable mixed-effects linear regression models which controlled county-level variables to determine the adjusted rates of spine surgeries for patients belonging to various race/ethnicity and income group combinations.

RESULTS

The study included 29,650 and 42,498 patients in the cervical and lumbar cohorts, respectively. In 2019, the county-level mean cervical and lumbar surgery rates were 3.88 and 5.19 surgeries per 10,000 individuals, respectively. There was a five-fold rate variation across NYS. In 2019, the adjusted cervical rates were 4.59 (White low-income), 4.96 (White high-income), 7.20 (Black low-income), 3.01 (Black high-income), 4.37 (Hispanic low-income), and 1.17 (Hispanic high-income). The adjusted lumbar rates were 5.49 (White low-income), 6.31 (White high-income), 9.43 (Black low-income), 2.47 (Black high-income), 4.22 (Hispanic low-income), and 2.02 (Hispanic high-income). The rates for low-income Black or Hispanic patients were significantly higher than their high-income counterparts. Low-income Black patients had the highest rates. Over the study period, the gap/difference increased significantly between high-income Hispanic and White individuals by 2.19 (95% confidence interval [CI]: -4.27, -0.10, p=.04) for cervical surgery; and between low-income Black and White individuals by 2.82 (2.82, 95% CI: 0.59, 5.06, p=.01) for lumbar surgery.

CONCLUSION

There are differences in the rates of spine surgery in New York State, among identifiable groups. Black individuals from poorer zip codes experience relatively higher spine surgery rates. Understanding the drivers of surgical rate variation is key to improving the equitable delivery of spine care. A better understanding of such rate variations could inform health policy.