Hospital competitive intensity and perioperative outcomes following lumbar spinal fusion

Abstract

Background context: Interhospital competition has been shown to influence the adoption of surgical techniques and approaches, clinical patient outcomes, and health care resource use for select surgical procedures. However, little is known regarding these dynamics as they relate to spine surgery.

Purpose: This investigation sought to examine the relationship between interhospital competitive intensity and perioperative outcomes following lumbar spinal fusion.

Study design/setting: This study used the Nationwide Inpatient Sample dataset, years 2003, 2006, and 2009.

Patient sample: Patients were included based on the presence of the International Classification of Disease, Ninth Edition, Clinical Modification (ICD-9-CM) codes corresponding to lumbar spinal fusion, as well as on the presence of data on the Herfindahl-Hirschman Index (HHI).

Outcome measures: The outcome measures are perioperative complications, defined using an ICD-9-CM coding algorithm.

Materials and methods: The HHI, a validated measure of competition within a market, was used to assess hospital market competitiveness. The HHI was calculated based on the hospital cachement area. Multiple regression was performed to adjust for confounding variables including patient age, gender, primary payer, severity of illness score, primary versus revision fusion, anterior versus posterior approach, national region, hospital bed size, location or teaching status, ownership, and year. Perioperative clinical outcomes were assessed based on ICD-9-CM codes with modifications.

Results: In total, 417,520 weighted patients (87,999 unweighted records) were analyzed. The mean cachement area HHI was 0.31 (range 0.099-0.724). The average patient age was 55.4 years (standard error=0.194), and the majority of patients were female (55.8%, n=232,727). The majority of procedures were primary spinal fusions (92.7%, n=386,998) and fusions with a posterior-only technique (81.5%, n=340,271). Most procedures occurred in the South (42.5%, n=177,509) or the Midwest (27.0%, n=112,758) regions. In the multiple regression analysis, increased hospital competitive intensity was associated with an increased total complication rate (odds ratio [OR] 1.52, p<.0001), device-related complications (OR 1.46, p=.0294), genitourinary complications (OR 2.15, p=.0091), infection (OR 3.48, p<.0001), neurologic complications (OR 1.69, p=.0422), total charges (+29%, p=.0034), and inpatient hospital length of stay (LOS) (+16%, p=.0012). The likelihood of complications at state-owned hospitals (OR 2.81, p=.0001) was more highly associated with HHI than at private, non-profit hospitals (OR 1.39, p=.0050). The occurrence of complications at urban teaching hospitals (OR 2.14, p<.0001) was generally more associated with HHI than at urban non-teaching hospitals (OR 1.19, p=.2457).

Conclusions: Increased interhospital competitive intensity is associated with increased odds of complications, increased total charges, and prolonged LOS following lumbar spine fusion. These differences are generally highest among state-owned and urban teaching hospitals. Differences in outcome related to hospital competition may be due to suboptimal resource allocation. Identifying differences in perioperative outcomes associated with hospital market competition is important in the contemporary environment of health care reimbursement reform and hospital consolidation. Perioperative outcome disparities between highly competitive and minimally competitive areas should be monitored and further studied.

Keywords: HHI; Health policy; Hospital competition; Lumbar fusion; NIS; Perioperative outcomes.