Elective spinal surgery in New South Wales adults, 2001-20, by procedure funding type: a cross-sectional study.

OBJECTIVE: To investigate elective rates of spinal fusion, decompression, and disc replacement procedures for people with degenerative conditions, by funding type (public, private, workers' compensation). DESIGN, SETTING: Cross-sectional study; analysis of hospitals admissions data extracted from the New South Wales Admitted Patient Data Collection. PARTICIPANTS: All adults who underwent elective spinal surgery (spinal fusion, decompression, disc replacement) in NSW, 1 July 2001 - 30 June 2020. MAIN OUTCOME MEASURES: Crude and age- and sex-adjusted procedure rates, by procedure, funding type, and year; annual change in rates, 2001-20, expressed as incidence rate ratios (IRRs). RESULTS: During 2001-20, 155 088 procedures in 129 525 adults were eligible for our analysis: 53 606 fusion, 100 225 decompression, and 1257 disc replacement procedures. The privately funded fusion procedure rate increased from 26.6 to 109.5 per 100 000 insured adults (per year: IRR, 1.06; 95% confidence interval [CI], 1.05-1.07); the workers' compensation procedure rate increased from 6.1 to 15.8 per 100 000 covered adults (IRR, 1.04; 95% CI, 1.01-1.06); the publicly funded procedure rate increased from 5.6 to 12.4 per 100 000 adults (IRR, 1.03; 95% CI, 1.01-1.06), and from 10.5 to 22.1 per 100 000 adults without hospital cover private health insurance (IRR, 1.03; 95% CI, 1.01-1.05). The privately funded decompression procedure rate increased from 93.4 to 153.6 per 100 000 people (IRR, 1.02; 95% CI, 1.01-1.03); the workers' compensation procedure rate declined from 19.7 to 16.7 per 100 000 people (IRR, 0.98; 95% CI, 0.96-0.99), and the publicly funded procedure rate did not change significantly. The privately funded disc replacement procedure rate increased from 6.2 per million in 2010-11 to 38.4 per million people in 2019-20, but did not significantly change for the other two funding groups. The age- and sex-adjusted rates for privately and publicly funded fusion and decompression procedures were similar to the crude rates. CONCLUSIONS: Privately funded spinal surgery rates continue to be larger than for publicly funded procedures, and they have also increased more rapidly. These differences may indicate that some privately funded procedures are unnecessary, or that the number of publicly funded procedures does not reflect clinical need.