Cost analysis of primary single-level lumbar discectomies using the Value Driven Outcomes database in a large academic center.

Background Context: Improving value is an established point of emphasis to reduce the rapidly rising health care costs in the United States. Back pain is a major driver of costs with a substantial fraction caused by lumbar radiculopathy. The most common surgical treatment for lumbar radiculopathy is microdiscectomy. Research is sparse regarding variables driving cost in microdiscectomies and often limited by cost data derived from payer-based Medicare data.

Purpose: To identify targets for cost reduction by determining variables associated with significant cost variation in microdiscectomies, using cost data derived from the Value Driven Outcomes tool and actual system costs.

Study Design: Single-center, retrospective study of prospectively collected registry data.

Patient Sample: Six hundred twenty-two patients identified by CPT code and manually screened for initial, unilateral, single-level lumbar discectomy performed between 2014 and 2018 at a single institution.

Outcome Measures: Primary outcome measures include total direct cost, clinical length of stay, and OR minutes. Total Direct Cost was further differentiated into facility and nonfacility costs.

Methods: Univariate and multivariate generalized linear models (GLM) were used to identify variables associated with variation in primary outcome measures. Costs were normalized by mean cost for patients with normal body mass index (BMI) and a healthy American Society of Anesthesiologists (ASA) classification. Average marginal effects were reported as percentage of normalized costs.

Results: Advanced age, male gender, Hispanic, black, unemployment, obesity, higher ASA class, insurance status, and being retired were positively associated with costs in univariate analysis. Asian, Native American, outpatient procedures, and being a student were associated with decreases in costs. In multivariate analysis, we found that obesity led to higher average marginal total direct (9%), total facility (15%), and facility OR costs (22%), as well as 24 more OR minutes per surgery. While being overweight was not associated with greater total direct costs, it was associated with higher total facility (8%), and facility OR costs (12%), with 11 more OR minutes per surgery. Age was associated with a longer LOS but not with OR costs. As expected, outpatient surgical costs, LOS, and OR time were significantly lower than inpatient procedures. Severe systematic disease was associated with greater total and nonfacility costs. In addition, Medicare patients had higher facility costs (14%) compared to privately insured patients.

Conclusions: Significant drivers of total direct cost in multivariate GLM analysis were obesity, severe systemic disease and inpatient surgery. Average LOS was increased due to age and inpatient status, conversely it was decreased by unemployment and retirement. Significant variables in OR time were male sex, Hispanic race and both obese and overweight BMIs.