Effect of obesity on cost per quality adjusted life years gained following anterior cervical discectomy and fusion in elective degenerative pathology.
BACKGROUND Obese 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. PURPOSE The aim of the present study was to determine cost utility following anterior cervical discectomy and fusion (ACDF) in obese patients. STUDY DESIGN This study analyzed prospectively collected data. PATIENT SAMPLE Patients undergoing elective ACDF for degenerative cervical pathology at a single academic institution were included in the study. OUTCOME MEASURES Cost and quality adjusted life years (QALYs) were the outcome measures. METHODS One 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) RESULTS There 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. CONCLUSIONS Anterior 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.
The spine journal official journal of the North American Spine Society