Revision surgery for adult spinal deformity has been shown to incur significantly lower surgical costs than primary surgery. In a study from Johns Hopkins, Baltimore, USA, which calculated cost-effectiveness in terms of quality-adjusted-life-years (QALYs), revision surgery was also shown to have a lower overall two-year cost and higher QALY gains, although these results were not significant. A cost-utility analysis showed revision surgery to be more cost-effective than primary surgery for adult spinal deformity.
The study was presented by Tina Raman, Baltimore, USA, at the 30th Annual Meeting of the North American Spine Society (NASS; 14-17 October, Chicago, USA). Raman et al computed cost-utility profiles for primary and revision surgery for adult spinal deformity at two years. They calculated QALYs by multiplying the number of years since surgery by a quality of life index made up of the SF-36 responses collected from patients, mapped on to EQ-5D utility scores.
Using precise data for surgical costs, and all costs for spine-related care over the two years following the initial surgeries, the overall costs of the procedures were gathered. This included all re-admissions, re-operations for complications and all physical therapy, among other things provided by hospitals.
The researchers used the complete two-year outcome data of 119 individuals—56 primary surgery patients and 63 revisionary surgery patients—with similar baseline parameters including age, gender and co-morbidity distributions.
No significant differences were found between the two groups in terms of number of levels fused or the length of hospital stay. Significantly more (42, n=56) post-year column osteotomies were performed in the primary surgery group, whilst a significantly greater number of three-column osteotomies were performed among the revision surgery group (40 pedicle subtraction, 14 vertebral column resection, n=56).
A significant improvement in all health-related quality-of-life parameters were observed in both groups, including SRS-22, ODI (Oswestry disability index) and utilities scores over the two years. The median QALY gains of each group were not significantly different, with the primary surgery group reporting 0.36 and the revision surgery group reporting 0.4. There was no difference in the rates of complications requiring reoperation between the two groups.
The median surgical costs for the procedures were US$103,000 for revision surgery and US$123,000 for primary surgery, with revision surgery working out significantly cheaper. The median two-year costs were lower again for the revision surgery group (US$116,000 vs US$138,000), but not significantly so.
Cost-per-QALY ratio was used as a cost-effectiveness index, considered against a threshold of three times the US GDP per capita. At the time of the study, this was calculated to be US$159,126. The cost-per-QALY of revision surgery was US$139,000, whilst the primary surgery group had a cost-per-QALY of US$198,000. The revision surgery group cost was below the cost-effectiveness threshold, whilst the cost for the primary surgery group was above it.
Raman, along with the senior author on the study Khaled Kebaish, emphasised the technical challenge of revision surgery, and the possibility that it may have a higher rate of major complications. They asserted the importance, however, of considering the cost-utility of these procedures for adult spinal deformity, given that the estimated cost of spinal fusion (US$12.8 billion) is the largest of any hospital-based surgery. Both kinds of surgery, Raman insists, are “inherently complex”, with high up front direct care costs. It is necessary, she says, to be able to justify the high expense of such procedures in a value-based healthcare system, “by demonstrating sustained QALY gains with decreasing costs over time.”
When asked why revision surgery was found to be cost-effective while primary surgery was not, Raman said that this may be partly due to a decrease in instrumentation costs, given the ability to use existing instruments in the revision surgery context. She said, “We also found that patients undergoing revision surgery had lower baseline health related quality of life measures than did primary surgery patients, and experienced greater delta QALY gain than did the primary surgery patients.”