Outcome & Cost of Lumbar Disc Replacement Versus Lumbar Fusion

Marc Du Bois

Peter Donceel

Painful lumbar disc degeneration is the leading cause of pain and disability in adults in the United States and in the rest of the world. This represents a large socioeconomic impact with estimates of more than $50 billion in direct and indirect health costs in the United States annually. In most cases, degenerative disc disease can be treated successfully nonoperatively (2,3). There are, however, substantial numbers of people who have failed exhaustive nonoperative treatments and who seek surgical solutions for their incapacitating back pain. Currently, fusion is a widely accepted treatment for degenerative disc disease. However, outcome measures of fusion surgery show mixed results, particularly in the long-term. The innovative properties that artificial discs bring to the treatment of spine disorders through spinal joint replacement, as opposed to fusion, include: (1) relief of pain by maintaining spinal motion; (2) prevention of adjacent segment disease by eliminating adjacent joint-segment rigidity, lessening the potential for future disease-related events and surgeries; and (3) the continuance of a lifestyle that more closely resembles a preillness state (2).

Objectives

We conducted a retrospective cohort study to establish whether disc replacement surgery can be performed with a better outcome comparable to combined discectomy and fusion. Our primary objective was to compare return to work rates after disc replacement surgery and combined discotomy and fusion. Determination of the costs associated with disc replacement surgery was our secondary objective.

Methods

Medical and financial claims data were abstracted from the administrative database of the Alliance of Christian Sickness Funds. This database is nationally representative for the Belgian population and includes data from 4,500,000 enrollees. All records including the reimbursement codes for combined discectomy and fusion between January 1, 2003, and December 31, 2003 were identified. A total of 310 patients met these criteria (fusion group). Next, 174 cases with disc replacement surgery were identified for the final dataset (disc replacement group). Patient age, gender, sick leave before surgery, employment state, and surgeon’s specialty were considered as covariates in the analysis.
Detailed cost data incurred during the hospital stay were collected. The costs represent the cost of anesthesia, radiology tests, nursing, lodging, and implants. All reported costs are in 2004 Euros.

A logistic regression model at the patient level was developed to determine the predictors of return to work Covariates significant at the 0.05 level in bivariate analyses were entered in the multivariate model in a stepwise manner. Statistical analyses were performed using SPSS 8.0.

Results

Patient Characteristics

Study patients consisted of 310 consecutive patients who underwent combined discectomy and fusion and 174 consecutive patients in whom a disc replacement surgery was performed. Baseline characteristics of the two treatment groups differed in several nonmedical factors shown to predict subsequent work outcomes (Table 33.1). Overall, the combined discectomy and fusion group encompassed significantly more female patients, and significantly less operations were performed by neurosurgeons. Importantly, these differences were taken into account by adjusting for these covariates in the logistic regression.

Outcomes

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