How Does Case Type, Length of Stay, and Comorbidities Affect Medicare DRG Reimbursement for Minimally Invasive Surgery (MIS) for Deformity?

Abstract

BACKGROUND CONTEXT: Minimally invasive surgery (MIS) uses techniques that differ from open surgery. MIS frequently uses anterior and posterior based procedures. Furthermore, MIS surgery may use posterior fixation without fusion. Hospital DRG coding and reimbursement is a separate system from physician professional CPT coding and reimbursement. Several distinct differences exist that significantly affect hospital reimbursement. Case type, length of stay, and concomitant medical comorbidities (CC) affect hospital reimbursement in spinal deformity surgery for both open and emerging MIS techniques. PURPOSE: This study aims to investigate Medicare DRG reimbursement for different types of MIS deformity surgery. STUDY DESIGN/SETTING: The Inpatient PPS PC Pricer (CMS.gov) was used to collect reimbursement data from 2015 for MIS surgical deformity procedures DRG's at our hospitals. PATIENT SAMPLE: Reimbursement data from 12 hospitals around USA. OUTCOME MEASURES: Reimbursement dollar amounts. METHOD(S): DRG-based reimbursement was obtained for MIS anterior, posterior and circumferential 1-level and multi-level fusion for listhesis and deformity cases with and without CC from 12 institutions throughout the US. The 3 most common MIS procedures were analyzed to compare reimbursement based on DRG coding: 1. fusion via anterior or posterior only; 2. fusion anterior with fixation posterior percutaneous (no dorsal fusion); 3. fusion combined anterior and posterior. RESULT(S): The number of levels fused does not affect the reimbursement for all cases. Cases 1 and 2 without CC, 3 day stay reimbursed $41,404 vs. 8 day reimbursed $42,808. Cases 1 and 2 with CCs, 3 day stay reimbursed $54,476 vs. 8 day stay reimbursed $55,881. Case 3 without CC, 3 day stay reimbursed $47,992 vs. 8 day stay reimbursed $49,397. Case 3 with CC, 3 day reimbursed $61,806 vs. 8 day reimbursed $63,212. The increased payment for an 8 day stay was $1,405 or $281 per day. If a deformity case 1 or 2 is coded incorrectly as a degenerative case the decrease in payment was $9,769 lower (-24%) with no CC and $22,841 lower (-42%) with CC. CONCLUSION(S): Regardless of direct costs, Medicare DRG based reimbursement was the same for single and multi-level MIS deformity cases. The use of posterior percutaneous fixation without dorsal fusion resulted in a 13- 16% lower reimbursement compared with the addition of a posterior arthrodesis. Coding a deformity case as degenerative by the hospital resulted in 24-42% lower DRG based reimbursement. In today's challenging environment it is important that physicians and hospitals better understand procedure and coding issues in order to be able to continue to offer complex spinal surgeries cost effectively to our patients.