RhBMP-2 versus iliac crest bone graft for lumbar spine fusion in patients over 60 years of age: a cost-utility study

Abstract

Study design: Randomized clinical trial.

Objective: To perform a cost-utility analysis using actual cost data from a randomized clinical trial of patients over 60 years old who underwent posterolateral fusion using either rhBMP-2/ACS or iliac crest bone graft (ICBG).

Summary background data: Bone morphogenetic protein has been shown to be an effective bone graft substitute for spine fusion. However, a clinical trial-based economic analysis of rhBMP-2/ACS compared with iliac crest bone graft has not been done.

Methods: Patients over 60 years old requiring decompression and posterolateral fusion were randomized to rhBMP-2/ACS (n = 50) or ICBG (n = 52). A dedicated hospital coder and research nurse tracked each patient to determine direct costs of inpatient care and all postoperative healthcare encounters up to 2 years after surgery. Preoperative and 2-year-postoperative SF-6D utility scores for each patient were determined. A decision tree was created, which included the probability of complications, need for additional treatments and revision surgery; and the costs associated with initial surgery and treatment for complications and additional treatment for continued spine symptoms; and utility scores.

Results: The mean total 2-year cost for care (excluding complication and additional spine treatment costs) was $34,235 in the ICBG group and $36,530 in the rhBMP-2/ACS group. For the entire group, the mean cost to treat a major complication was $10,888, the cost of revision surgery for nonunion was $46,852, and additional treatment for spine-related events was $5892. In the ICBG group, 8 patients had complications; 20 had additional interventions, 5 of whom required revision for nonunion. In the rhBMP-2/ACS group, 6 patients had complications, 10 had additional interventions, and 1 required revision for nonunion. The cost of using rhBMP-2/ACS was $39,967 with a 0.11 mean improvement in SF-6D; and for ICBG the cost was $42,286 with a mean improvement of 0.10 in SF-6D.

Conclusion: There are more complications, increased need for additional treatment and revision surgery in patients over 60 years old receiving ICBG compared with rhBMP-2/ACS. This may account for higher costs and lower improvements in utility seen in patients receiving ICBG compared with rhBMP-2/ACS in this study population.