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Matthew Varacallo, MD

AAOS Now

Published 5/1/2019
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Terry Stanton

Study Examines Readmission Risk Factors, Cost Drivers in Ankle Fractures

Variables include higher ASA score, treatment by podiatry service
A study that sought to determine the independent clinical variables associated with increasing total costs in a 90-day episode of care (EOC) for the management of isolated ankle fractures requiring surgery found that patients with an American Society of Anesthesiologists (ASA) physical status classification score ≥ 3 and patients treated by the podiatry service as opposed to the orthopaedic team were at an increased risk of hospital readmission at both 30- and 90-days post discharge. Such patients, along with male patients, were independently associated with increasing total post-discharge costs in the 90-day EOC.

The data, presented at the AAOS 2018 Annual Meeting by Matthew Varacallo, MD, of Drexel University, also revealed that outpatient cases were associated with about a one-third reduction in total costs compared to the inpatient subgroup.

The study involved 299 patients with ankle injury patterns that were mostly unimalleolar (n = 115, 38.4 percent) or bimalleolar (n = 111, 37.1 percent) fractures; the remaining fractures were trimalleolar. The average patient age was 43 years, 57.9 percent of patients were female, and 87.3 percent of patients had government-based insurance at the time of injury.

More than two-thirds (67.2 percent) of cases were performed in the inpatient setting, and the average length of stay was 2.7 days. Overall, the orthopaedic surgery service managed 194 of the 299 cases (64.9 percent), including a larger relative proportion of bimalleolar- and trimalleolar-type injuries, while nearly two-thirds of patients treated by podiatry had unimalleolar injuries. Treatment by the podiatry service resulted in significantly more returns to the emergency department (P < 0.001), higher readmission rates at 30 and 90 days (P < 0.001 for both), and more returns to the operating room (OR) to manage complications related to the primary procedure (P = 0.019).

Costs and readmissions
The mean index admission cost was $14,048.65. Outpatient cases were significantly less expensive compared to the inpatient subgroup ($10,164.22 versus $15,942.55, respectively; P < 0.001). When factoring in all post-discharge utilization encounters, the 90-day associated costs averaged $9,478.25, and were significantly higher in patients treated by the podiatry service ($3,175.08 versus $14,380.72, P = 0.002). Furthermore, in the final multivariate model, male sex was an independent risk factor for increasing total post-discharge costs.

Unplanned readmission rates were 5.4 percent (16/299) and 6.7 percent (20/299) at 30 and 90 days, respectively. Independent risk factors for 30- and 90-day hospital readmission included treatment by the podiatry service and an ASA score ≥ 3. In addition, Dr. Varacallo said, reasons for readmission were infection and/or wound-related complications in 13 of the 20 (65 percent) encounters. Other reasons for hospital readmission included exacerbation of pre-existing medical conditions (5/20, 25 percent) and trauma admissions unrelated to the primary procedure (2/20, 10 percent).

Dr. Varacallo said he and his colleagues undertook the study in part to examine the implications of the healthcare environment transitioning to cost-containment strategies in 90-day EOC periods. “Our group wished to establish a proactive position at the forefront of the expansion of these models into the field of isolated lower extremity trauma,” he explained.

“One of my biggest areas of interest is risk factor analysis for increasing costs and hospital readmissions across the 90-day period and applying ‘big data’ at the institutional level,” he said. “While big data and large nationwide/international database studies play a critical role in the provisional identification of at-risk clinical variables, my fear is that we inherently apply a one-size-fits-all approach across all hospital systems and regions of practice. From an institution’s perspective, the ‘big data’ needs to be tailored to yield the even more valuable ‘little data.’”

According to Dr. Varacallo, the study yielded the following major clinical takeaways:

  • Appropriate consideration should be given to managing ankle fractures in the outpatient setting.
  • Our emergency department physicians should consider our results when deciding which service (orthopaedics versus podiatry) is most appropriate for referral.
  • Higher ASA scores independently increase the unplanned hospital readmission rates.

He noted the findings indicate that, “the 90-day EOC costs associated with returns to the ED, unplanned hospital readmissions, and especially returns to the operating room add a potentially exorbitant amount to a theoretical bundled payment period, and the risk factors behind these costs need to be considered at the institutional level as these risk factors most certainly will vary from hospital system to hospital system.”

Implications
The study authors observed that “understanding the readmission profile has important implications for developing future cost containment strategies.” They noted that two-thirds of hospital readmissions in their group were for infection- and/or wound-related complications, and of the nine cases returned to the OR, all were infection-based and involved the primary surgical site. “Previous literature has already tagged surgical site infections and subsequent management to be one of the costliest readmission diagnoses,” they wrote.

With respect to the issue of implications for future bundled payment initiatives, the authors wrote, “The goal of bundled payment models is to encourage physicians, hospitals, and all healthcare providers to provide more efficient, cost-effective care over the entire 90-day EOC.” They noted that although bundled payments in orthopaedics are largely established for total joint arthroplasty (TJA), “some hospitals already experience the triggered bundles for 90-day management of hip fractures.”

The authors observed that regional and geographical variations in patient populations and treatment practices “highlight the importance of critical assessment of the various large, nationwide studies describing risk factors as potentially generalizable conclusions.” They noted that previously they advocated a similar institution-based approach to delineate risk factors in elective TJA readmission. “This provides an institution with a customized analysis of clinical risk factors applicable in potential bundled payment hospital initiatives,” they wrote.

In future studies, Dr. Varacallo said, “I want to continue this trend of advocating for the ‘little data’ in this increasingly popular era of ‘big data.’ We do not live in a one-size-fits-all society, and I and my group will continue to push for the individual institution’s voice amidst these controversial topics. We would like to explore the influence of additional clinical risk factors in this specific treatment category and analyze other future potential bundled payment models.”

Dr. Varacallo’s coauthors of “Cost Determinants in the 90-Day Management of Isolated Ankle Fractures at a Large Urban Academic Hospital” are Patrick Mattern, BS; Jonathan Acosta, BS; Nader Toossi, MD; Kevin Denehy, MD; and Susan Harding, MD.

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org.