Refining Risk-Adjustment of 90-day Costs Following Surgical Fixation of Ankle Fractures: Implications for a Bundled Payment Model
Authors: Malik Azeem Tariq , Quatman Carmen E , Ly Thuan V. , Phieffer Laura , Khan Safdar N 
Published: October 2019

Category: Trauma Introduction/Purpose: Current literature revolving around understanding cost-determinants of 90-day payments following ankle fractures is limited to single-institution studies. As the current healthcare model transitions from fee-for-service to value- based payments, risk-adjustment of 90-day payments will be a key factor driving success of these bundled payment models. The current study, utilizes a national Medicare database, to understand patient-level, procedure-level and state-level variation in 90-day payments following open reduction internal fixation (ORIF) of isolated ankle fractures. Methods: The 2005-2014 5% Medicare SAF (Standard Analytical Files) database was queries using Current Procedural Terminology codes to identify patients undergoing open reduction internal fixation (ORIF) for uni-malleolar (27766, 27769, 27792), bi-malleolar (27814) and tri-malleolar (27822, 27823) ankle fractures. Patients with polytrauma or those undergoing a concurrent surgical fixation of the upper extremity, hip, femur, knee or tibia were removed from the study to capture a relevant cohort of isolated ankle fracture patients. All payments starting from day 0 of surgery up to day 90 post-operatively were used to calculate 90-day costs. Patients with missing data were excluded. Multi-variate linear regression modeling was used to derive marginal cost-impact of patient-level (age, gender, co-morbidities), procedure-level (fracture type, morphology, location of surgery, concurrent ankle arthroscopy and syndesmotic fixation) and state-level factors on 90-day costs following surgery. Results: Following application of inclusion/exclusion criteria, a total of 6,499 patients were included in the study. The risk- adjusted 90-day price of a non-geriatric (age<65) female patient undergoing outpatient ORIF for a closed uni-malleolar ankle fracture was $8,915 ± $1,054. Individuals aged 65-69 vs. <65 had significantly lower costs (-$1,967). Procedure-level factors associated with significant marginal cost-increases were inpatient surgery (+$5,577), tri-malleolar fracture (+$1,082) and syndesmotic fixation (+$2,822). The top 5 co-morbidities with largest marginal cost-increases were chronic kidney disease (+$8,897), malnutrition (+$7,908), obesity (+$5,362), cerebrovascular disease/stroke (+$4,159) and anemia (+$3,087). Significant state-level variation in 90-day costs was seen with Nevada (+$6,371), Massachusetts (+$4,497), Oklahoma (+$4,002), New Jersey (+$3,802) and Maryland (+$3,043) having the highest marginal cost-increase and Idaho (-$6,025) having the lowest. Conclusion: Using a national administrative claims database, the study identifies numerous patient-level, procedure-level and state-level factors that significantly contribute to the cost-variation seen in 90-day payments following ORIF for ankle fracture. Risk adjustment of 90-day costs will become a necessity as bundled-payment models begin to take over the current fee-for-service model in fracture patients.