P98. An economic evaluation of early term and late term complications following adult spinal deformity correction

BACKGROUND CONTEXT Adult spinal deformity (ASD) corrective surgery is often a highly invasive procedure portending patients to both immediate and long-term complications. However, the impact of each of these complications and their timing of occurrence on cost-utility has yet to be assessed. PURPOSE To compare the economic impact of certain complications before and after two years following ASD surgery. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 689 ASD Patients. OUTCOME MEASURES Complications, cost utility. METHODS ASD patients with minimum 3-year and up to 5-year data were included. Complication groups were defined as follows: 1) any complication, 2) major, 3) medical [cardiac event, ileus, etc.], 4) mechanical [implant failure, rod fracture, 5) radiographic [PJK, pseudarthrosis, adjacent segment disease], and 6) reoperation. Complications were stratified by occurrence before or after two years postoperatively. Published methods converted ODI to SF-6D. QALYs utilized a 3% discount rate for residual decline. Cost was calculated using the PearlDiver database and assessed for Complications and Comorbidities and Major Complications and Comorbidities according to CMS.gov definitions. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for services within a 30-day window. Marginalized means for utility gained and Cost per QALY were calculated, controlling for age, history of prior fusion, and baseline deformity and disability. RESULTS There were 244 ASD patients included, with an average age of 59±15 yrs, that were predominantly female (77%) and a high CCI (1.7±1.7). By 2Y, comp rates: 76% 1 complication, 18% major, 16% medical, 16% neurological, 50% radiographic, 5% infection and 20% mechanical, and 64 patients (26%) required reoperation. After 2Y, comp rates: 32% 1 complication, 4% major, 0.4% medical, 2% neurological, 22% radiographic, and 5% mechanical, and 6 patients (2.5%) required reoperation. Overall, any complications occurring after 2 years had a lower cost and cost-utility than those before two years, while major complications happening after two years had worse cost-utility due to lower utility gained (0.320 vs. 0.441, p=.1). Patients developing PJK by and after two years had the lowest cost-utility of any time points. When examining complications occurring before 2 years, patients suffering a mechanical complication accrued the highest overall cost ($130,482.22) followed by infection and PJF. Those suffering a mechanical complication also had the highest utility gained of any complication before 2 years, lowering their cost-utility below that of infection. In contrast, despite having a lower utility gained, those suffering a mechanical complication after 2 years had a lower cost ($109,197.71 vs $130,482.22, p=.041) and cost-utility overall. Similarly, patients developing PJF after 2 years accrued a higher utility gained, lower cost and cost-utility ($77,227.84 vs. $96,873.57, p=.038) than those developing PJF before 2 years. CONCLUSIONS Mechanical complications had the single greatest impact on cost and cost-utility when occurring before or after 2 years following correction of adult spinal deformity. However, mechanical and radiographic complications occurring after 2 years had less detrimental effects on both cost and cost-utility. This study increases our understanding of the complications following adult spinal deformity correction in order to mitigate the outcomes that most drastically impact the economic benefit of surgical intervention. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Adult spinal deformity (ASD) corrective surgery is often a highly invasive procedure portending patients to both immediate and long-term complications. However, the impact of each of these complications and their timing of occurrence on cost-utility has yet to be assessed. To compare the economic impact of certain complications before and after two years following ASD surgery. Retrospective. A total of 689 ASD Patients. Complications, cost utility. ASD patients with minimum 3-year and up to 5-year data were included. Complication groups were defined as follows: 1) any complication, 2) major, 3) medical [cardiac event, ileus, etc.], 4) mechanical [implant failure, rod fracture, 5) radiographic [PJK, pseudarthrosis, adjacent segment disease], and 6) reoperation. Complications were stratified by occurrence before or after two years postoperatively. Published methods converted ODI to SF-6D. QALYs utilized a 3% discount rate for residual decline. Cost was calculated using the PearlDiver database and assessed for Complications and Comorbidities and Major Complications and Comorbidities according to CMS.gov definitions. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for services within a 30-day window. Marginalized means for utility gained and Cost per QALY were calculated, controlling for age, history of prior fusion, and baseline deformity and disability. There were 244 ASD patients included, with an average age of 59±15 yrs, that were predominantly female (77%) and a high CCI (1.7±1.7). By 2Y, comp rates: 76% 1 complication, 18% major, 16% medical, 16% neurological, 50% radiographic, 5% infection and 20% mechanical, and 64 patients (26%) required reoperation. After 2Y, comp rates: 32% 1 complication, 4% major, 0.4% medical, 2% neurological, 22% radiographic, and 5% mechanical, and 6 patients (2.5%) required reoperation. Overall, any complications occurring after 2 years had a lower cost and cost-utility than those before two years, while major complications happening after two years had worse cost-utility due to lower utility gained (0.320 vs. 0.441, p=.1). Patients developing PJK by and after two years had the lowest cost-utility of any time points. When examining complications occurring before 2 years, patients suffering a mechanical complication accrued the highest overall cost ($130,482.22) followed by infection and PJF. Those suffering a mechanical complication also had the highest utility gained of any complication before 2 years, lowering their cost-utility below that of infection. In contrast, despite having a lower utility gained, those suffering a mechanical complication after 2 years had a lower cost ($109,197.71 vs $130,482.22, p=.041) and cost-utility overall. Similarly, patients developing PJF after 2 years accrued a higher utility gained, lower cost and cost-utility ($77,227.84 vs. $96,873.57, p=.038) than those developing PJF before 2 years. Mechanical complications had the single greatest impact on cost and cost-utility when occurring before or after 2 years following correction of adult spinal deformity. However, mechanical and radiographic complications occurring after 2 years had less detrimental effects on both cost and cost-utility. This study increases our understanding of the complications following adult spinal deformity correction in order to mitigate the outcomes that most drastically impact the economic benefit of surgical intervention.