Effect of obesity on cost per quality-adjusted life years gained following anterior cervical discectomy and fusion in elective degenerative pathology

Abstract

BackgroundObese patients have greater comorbidities along with higher risk of complications and greater costs after spine surgery, which may result in increased cost and lower quality of life compared with their non-obese counterparts. PurposeThe aim of the present study was to determine cost-utility following anterior cervical discectomy and fusion (ACDF) in obese patients. Study DesignThis study analyzed prospectively collected data. Patient SamplePatients undergoing elective ACDF for degenerative cervical pathology at a single academic institution were included in the study. Outcome MeasuresCost and quality-adjusted life years (QALYs) were the outcome measures. MethodsOne- and two-year medical resource utilization, missed work, and health state values (QALYs) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national payment amounts (direct cost). Patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Total cost (direct+indirect) was used to compute cost per QALY gained. Patients were defined as obese for body mass index (BMI) ≥35 based on the WHO definition of class II obesity. A subgroup analysis was conducted in morbidly obese patients (BMI≥40). ResultsThere were significant improvements in pain (neck pain or arm pain), disability (Neck Disability Index), and quality of life (EuroQol-5D and Short Form-12) at 2 years after surgery (p<.001). There was no significant difference in post-discharge health-care resource utilization, direct cost, indirect cost, and total cost between obese and non-obese patients at postoperative 1-year and 2-year follow-up. Mean 2-year direct cost for obese patients was $19,225±$8,065 and $17,635±$6,413 for non-obese patients (p=.14). There was no significant difference in the mean total 2-year cost between obese ($23,144±$9,216) and non-obese ($22,183±$10,564) patients (p=.48). Obese patients had a lower mean cumulative gain in QALYs versus non-obese patients at 2-years (0.34 vs. 0.42, p=.32). Two-year cost-utility in obese ($68,070/QALY) versus non-obese patients ($52,816/QALY) was not significantly different (p=.11). Morbidly obese patients had lower QALYs gained (0.17) and higher cost per QALYs gained ($138,094/QALY) at 2 years. ConclusionsAnterior cervical discectomy and fusion provided a significant gain in health state utility in obese patients, with a mean 2-year cost-utility of $68,070 per QALYs gained, which can be considered moderately cost-effective. Morbidly obese patients had lower cost-effectiveness; however, surgery does provide a significant improvement in outcomes. Obesity, and specifically morbid obesity, should to be taken into consideration as physician and hospital reimbursements move toward a bundled model.