Selection of patients for ambulatory lumbar discectomy: results from four US states

Background context: There is a persistent trend for more outpatient lumbar discectomies in the United States.

Purpose: To investigate the characteristics of the patients selected for ambulatory procedures.

Study design: Retrospective cohort study.

Patient sample: Forty-seven thousand one hundred twenty-five patients who underwent outpatient and 102,592 patients undergoing inpatient lumbar discectomies and were were registered in the State Ambulatory Surgery Database (SASD) and State Inpatient Database (SID), respectively, for New York, California, Florida, and North Carolina from 2005 to 2008.

Outcome measures: Rate of outpatient procedures, 30-day readmissions, and hospital charges.

Methods: We performed a retrospective cohort study involving patients who underwent outpatient and inpatient lumbar discectomies and were registered in SASD and SID, respectively, for New York, California, Florida, and North Carolina from 2005 to 2008. Logistic regression models were used to demonstrate the association of socioeconomic factors with the odds of undergoing an outpatient procedure.

Results: Male gender (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.03-1.08), private insurance (OR, 1.93; 95% CI, 1.86-2.01), lower Charlson Comorbidity Index (OR, 4.04; 95% CI, 3.17-5.16), and higher volume hospitals (OR, 1.06; 95% CI, 1.04-1.08) were significantly associated with outpatient procedures. Higher income (OR, 0.83; 95% CI, 0.81-0.85), older age (OR, 0.996; 95% CI, 0.995-0.997), coverage by Medicaid (OR, 0.89; 95% CI, 0.83-0.96), African Americans (OR, 0.65; 95% CI, 0.60-0.70), and other minority races were associated with decreased odds of outpatient procedures. The rate of 30-day postoperative readmissions was higher among inpatients. Institutional charges were significantly lower for outpatient lumbar discectomies. The median charge for inpatient surgery was $24,273 as compared with $11,339 for the outpatient setting (p<.0001).

Conclusions: Access to ambulatory lumbar discectomies appears to be more common for younger, white, male patients, with private insurance and less comorbidities, in the setting of higher volume hospitals. Further investigation is needed in the direction of mapping these disparities for appropriate resource utilization.