Evaluating outpatient versus inpatient costs in endophthalmitis management.

PURPOSE: To assess the cost savings that would result from 1) implementing the treatment guidelines of the Endophthalmitis Vitrectomy Study (EVS) and 2) performing procedures on an outpatient rather than an inpatient basis, and to compare the savings to the cost of conducting the EVS.

METHODS: The coding algorithms for four endophthalmitis treatment groups were obtained from Patient Financial Services at the Anne Bates Leach Eye Hospital (ABLEH) and national Medicare averages were consulted for reimbursements in 2000 dollars. The four groups were: 1) inpatient pars plana vitrectomy (PPV) with intravenous antibiotics; 2) outpatient PPV; 3) inpatient vitreous tap with intravenous antibiotics; and 4) outpatient vitreous tap. Physician reimbursements were calculated using International Classification of Diseases-9 (ICD-9) diagnoses and Current Procedural Terminology (CPT) codes. Facility reimbursements were calculated using ICD-9 diagnoses and Diagnosis-Related Group codes for inpatient procedures versus Ambulatory Payment Classification codes for outpatient procedures. The annual savings in reimbursements were estimated for a range of annual incidence rates of endophthalmitis assuming ABLEH financial data across all patients in the United States, and the savings into the future as well as the total expenses of conducting the EVS from 1989 to 1995 were summed in 2000 dollars using a net present value analysis based on the Bureau of Labor Statistics consumer price indices.

RESULTS: Facility reimbursements are significantly higher for procedures performed on an inpatient compared to an outpatient basis (P < 0.001). Treating endophthalmitis according to the EVS guidelines on an outpatient basis would be associated with an estimated $1.5 to $7.8 million reduction in reimbursements per year. The cost of the EVS in 2000 dollars was $4.0 million.

CONCLUSIONS: Implementing the treatment guidelines of the EVS on an outpatient basis may result in significant cost savings--savings that may cover the entire cost of the EVS in 3 years.