The Clinical and Financial Consequences of the Centers for Medicare and Medicaid Services' Two-Midnight Rule in Total Joint Arthroplasty

Should Chronological Age be a Consideration in Patients Undergoing Elective Primary Total Knee Arthroplasty?

BACKGROUND

The optimal time for total knee arthroplasty (TKA) requires a balance between patient disability and health state to minimize complications. While chronological age has not been shown to be predictive of complications in elective surgical patients, there is a point beyond which even optimized elderly patients would be at increased risk for complications. The purpose of this study was to examine the impact of chronological age on complications following primary TKA.

METHODS

Using an administrative database, the records of 2,129,191 patients undergoing elective unilateral TKA between 2006 and 2021 were reviewed. The primary outcomes of interest were cardiac and pulmonary complications, and their relationship to the Charlson-Deyo Comorbidity Index (CDI) and chronological age. Secondary outcomes included risk of renal, neurologic, infection, and intensive care utilization postoperatively. The results were analyzed using a graphical method. The impact of chronological age as a modifier of overall risk for complications was modeled as a continuous variable. An age cutoff threshold of 80 years was also assigned for clinical convenience.

RESULTS

The risk of complications correlated more closely to the CDI (odds ratio (OR) 1.37 to 2.1) than chronological age (OR 1.0 to 1.1) across the various complications [Table 1. However, beyond age 80 years, the risks of cardiac, pulmonary, renal, and cerebrovascular complications were significantly increased for all CDI categories (OR 1.73 to 3.40) compared to patients below age 80 years [Table 2] [Figures 1A and 1B].

CONCLUSIONS

Chronologic age can impact the risk of complications even in well-optimized elderly patients undergoing primary TKA. As arthroplasty continues to transition to outpatient settings and inpatient denials increase, these results can help patients, physicians, and payors mitigate risk while optimizing the allocation of resources.

Outpatient vs. inpatient designation in total hip arthroplasty: can we predict who will require hospitalization?

INTRODUCTION

Following removal of total hip arthroplasty (THA) from the inpatient only (IPO) list by the Center for Medicare Services (CMS), arthroplasty surgeons face increased pressure to perform procedures on an outpatient (OP) basis. The purposes of the present study were to compare patients booked for THA as OP who required conversion to IP status postoperatively, to patients who were booked as, and remained OP, and to identify factors predictive of conversion from OP to IP status.

METHODS

We retrospectively reviewed all patients who underwent a primary THA at our institution between January 1, 2020 and April 26, 2022. All patients included were originally scheduled for OP surgery and were separated based on conversion to IP status postoperatively. Multiple regression analyses were used to determine the significance of all perioperative variables. Modeling via binary logistic regressions were used to determine factors predictive of status conversion.

RESULTS

Of 1,937 patients, 372 (19.2%) designated as OP preoperatively required conversion to IP status postoperatively. These patients had significantly higher facility discharge rates (P < 0.001) and 90-day readmission rates (P = 0.024). Patients aged 65 and older (P < 0.001), females (P < 0.001), patients with Black/African American race (P = 0.027), with a recovery room arrival time after 12 pm (P < 0.001), with a BMI > 30 kg/m2 (P = 0.001), and with a Charlson Comorbidity Index (CCI) ≥ 4 (P = 0.013) were Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation more likely to require conversion to IP designation. Marital status and time of procedure were also significant factors, as patients who were married (P < 0.001) and who were the first case of the day (P < 0.001) were less likely to be converted to IP.

CONCLUSION

Several factors were identified which could help determine appropriate hospital designation status at the time of surgical booking to ultimately avoid insurance claim denials. These included BMI, certain demographic factors, CCI ≥ 4, and patients 65 or older.

LEVEL III EVIDENCE

Retrospective Cohort Study.

The Immediate Impact of Total Knee Arthroplasty Removal From the Medicare Inpatient-Only List on Patient Derived Functional Outcomes and Hospital Satisfaction

BACKGROUND

Total knee arthroplasty (TKA) is the standard of treatment for end-stage knee osteoarthritis. On January 1, 2018, the Centers for Medicare and Medicaid (CMS) officially removed TKA from their inpatient-only list. The clinical impact of this change is not fully understood yet.

METHODS

Electronic records were retrospectively reviewed for patients who underwent TKA between January 1 to June 30, 2017, or January 1 to June 30, 2018. Patients completed Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement surveys which assessed patient reported outcomes prior to and following TKA. Hospital statistics for the 2 time points were determined and compared. This was a single institution study resulting in 351 patients in the pre-CMS change group and 350 patients in the post-CMS change group.

RESULTS

Analysis of the pre-CMS and post-CMS transition cohorts indicated no significant difference in activities of daily living (ADLs), pain, or pain catastrophizing scale preoperatively or 12-months postoperatively. Additionally, there was no difference in the median change between preoperative and postoperative ADL scores (P = .866), yet pain scores approached significance with a P value of .054. The pre-CMS transition group stayed significantly longer in the hospital postoperatively and was more commonly discharged to a skilled nursing facility. No difference was seen in 30-day readmission rates (P = .253).

CONCLUSIONS

Results showed that patients had similar scores for ADL, quality of life, pain, and pain catastrophizing 12-months following their TKA. Movement of TKA from the Medicare inpatient only list did not have an immediate negative impact for patient reported outcomes and 30-day readmissions at our institution in the 6-month transition period.

Lower Revenue Surplus in Medicare Advantage Versus Private Commercial Insurance for Total Joint Arthroplasty: An Analysis of a Single Payor Source at One Institution

BACKGROUND

Since the Affordable Care Act was passed in 2010, reductions in Medicare reimbursement have led to larger discrepancies between the relative cost of Medicare patients and privately insured patients. The purpose of this study was to compare reimbursement between Medicare Advantage and other insurance plans in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

Patients of a single commercial payor source who underwent primary unilateral TKA or THA at 1 institution between the dates of January 4 and June 30, 2021, were included (n = 833). Variables included insurance type, medical comorbidities, total costs, and surplus amounts. The primary outcome measure was revenue surplus between Medicare Advantage and Private Commercial plans. t-tests, Analyses of Variance, and Chi-Squared tests were used for analysis. A THA represented 47% of cases and a TKA 53%. Of these patients, 31.5% had Medicare Advantage and 68.5% had Private Commercial insurance. Medicare Advantage patients were older and had higher medical comorbidity risk for both TKA and THA.

RESULTS

Significant differences were observed in medical costs between Medicare Advantage and Private Commercial insurance for THA ($17,148 versus $31,260, P < .001) and TKA ($16,723 versus $33,593, P < .001). Additionally, differences were seen in surplus amounts between Medicare Advantage and Private Commercial insurance for THA ($3,504 versus $7,128, P < .001) and TKA ($5,581 versus $10,477, P < .001). Deficits were higher in Private Commercial patients undergoing TKA (15.2 versus 6%, P = .001).

CONCLUSION

The lower average surplus associated with Medicare Advantage plans may lead to financial strain on provider groups who care for these patients and face additional overhead costs.

Can machine learning models predict prolonged length of hospital stay following primary total knee arthroplasty based on a national patient cohort data?

INTRODUCTION

The total length of stay (LOS) is one of the biggest determinators of overall care costs associated with total knee arthroplasty (TKA). An accurate prediction of LOS could aid in optimizing discharge strategy for patients in need and diminishing healthcare expenditure. The aim of this study was to predict LOS following TKA using machine learning models developed on a national-scale patient cohort.

METHODS

The ACS-NSQIP database was queried to acquire 267,966 TKA cases from 2013 to 2020. Four machine learning models-artificial neural network (ANN), random forest, histogram-based gradient boosting, and k-nearest neighbor were trained and tested on the dataset for the prediction of prolonged LOS (LOS exceeded the 75th of all values in the cohort). The model performance was assessed by discrimination (area under the receiver operating characteristic curve [AUC]), calibration, and clinical utility.

RESULTS

ANN delivered the best performance among the four models. ANN distinguished prolonged LOS in the study cohort with an AUC of 0.71 and accurately predicted the probability of prolonged LOS for individual patients (calibration slope: 0.82; calibration intercept: 0.03; Brier score: 0.089). All models demonstrated clinical utility by generating positive net benefits in decision curve analyses. Operation time, pre-operative transfusion, pre-operative laboratory tests (hematocrit, platelet count, and white blood cell count), and BMI were the strongest predictors of prolonged LOS.

CONCLUSION

ANN demonstrated modest discrimination capacity and excellent performance in calibration and clinical utility for the prediction of prolonged LOS following TKA. Clinical application of the machine learning models has the potential to improve care coordination and discharge planning for patients at high risk of extended hospitalization after surgery. Incorporating more relevant patient factors may further increase the models' prediction strength.

Machine Learning Models Based on a National-Scale Cohort Identify Patients at High Risk for Prolonged Lengths of Stay Following Primary Total Hip Arthroplasty

BACKGROUND

Existing machine learning models that predicted prolonged lengths of stay (LOS) following primary total hip arthroplasty (THA) were limited by the small training volume and exclusion of important patient factors. This study aimed to develop machine learning models using a national-scale data set and examine their performance in predicting prolonged LOS following THA.

METHODS

A total of 246,265 THAs were analyzed from a large database. Prolonged LOS was defined as exceeding the 75th percentile of all LOSs in the cohort. Candidate predictors of prolonged LOS were selected by recursive feature elimination and used to construct four machine learning models-artificial neural network, random forest, histogram-based gradient boosting, and k-nearest neighbor. The model performance was assessed by discrimination, calibration, and utility.

RESULTS

All models exhibited excellent performance in discrimination (area under the receiver operating characteristic curve [AUC] = 0.72 to 0.74) and calibration (slope: 0.83 to 1.18, intercept: -0.01 to 0.11, Brier score: 0.185 to 0.192) during both training and testing sessions. The artificial neural network was the best performer with an AUC of 0.73, calibration slope of 0.99, calibration intercept of -0.01, and Brier score of 0.185. All models showed great utility by producing higher net benefits than the default treatment strategies in the decision curve analyses. Age, laboratory tests, and surgical variables were the strongest predictors of prolonged LOS.

CONCLUSION

The excellent prediction performance of machine learning models demonstrated their capacity to identify patients prone to prolonged LOS. Many factors contributing to prolonged LOS can be optimized to minimize hospital stay for high-risk patients.

Patient Designation Prior to Total Knee Arthroplasty: How Can Preoperative Variables Impact Postoperative Status?

BACKGROUND

Removal of total knee arthroplasty (TKA) from the inpatient only list has led to a greater focus on outpatient (OP) procedures. However, the impact of OP-centered models in at-risk patients is unclear. Therefore, the current analysis investigated the effect of conversion from OP to inpatient (IP) status on postoperative outcomes and determined which factors put patients at risk for status change postoperatively.

METHODS

We retrospectively reviewed all patients who underwent a primary TKA at our institution between January 2, 2018, and April 26, 2022. All patients included were originally scheduled for OP surgery and were separated based on conversion to IP status postoperatively. Multiple regression analyses were used to determine the significance of all perioperative variables. Modeling via binary logistic regressions was used to determine factors predictive of status conversion.

RESULTS

Of the 2,313 patients originally designated for OP TKA, 627 (27.1%) required a stay of 2 midnights or longer. Patients in the IP group had significantly higher facility discharge rates (P < .001) compared to the OP group. Factors predictive of conversion included age of 65 years and older (P < .001), women (P < .001), arriving at the postanesthesia care unit after 12 pm (P < .001), body mass index greater than 30 (P = .004), and Charlson Comorbidity Index of 4 and higher (P = .004). Being the first case of the day (P < .001) and being married (P < .001) were both protective against conversion.

CONCLUSION

Certain intrinsic patient factors may predispose a patient to an IP stay, and an understanding of predisposing factors which could lead to IP conversion may improve perioperative planning moving forward.

RAPT Scores Predict Inpatient Versus Outpatient Status and Readmission Rates After IPO Changes for Total Joint Arthroplasty: An Analysis of 12,348 Cases

BACKGROUND

Changes to Medicare's Inpatient Only List (IPO) and factors associated with the COVID pandemic have led to more total joint arthroplasty (TJA) patients to be designated as outpatient (OP). This potentially complicates postoperative care for patients with lower functional status and poor social support. These factors make the decision between OP versus inpatient (IP) designation particularly challenging for healthcare teams. The Risk Assessment and Prediction Tool (RAPT) was designed to indicate patient risk for needing posthospital discharge to facility and considers social and functional factors. The purpose of this study is to 1) evaluate the correlation of RAPT as a clinical tool to aid decision-making regarding OP versus IP for Total Hip and Knee Arthroplasty (THA and TKA), 2) assess the impact of recent changes to the IPO and the COVID pandemic on OP TJA readmission rates, and 3) determine whether 90-day readmissions are correlated with RAPT scores after OP TJA.

METHODS

We identified all elective TKA and THA patients from 2015 through 2021 in our electronic health record at our large, urban, academic health system. Fracture patients were excluded. For those patients with available RAPT scores, we determined OP and IP designations, with IP defined as those with length-of-stay 2 midnights or more. We performed subanalysis of OP between same-day and next-day discharge. RAPT scores and readmission rates were compared at time points related to changes in the IPO: before TKA removal in 2018 (period A), from 2018 until THA removal in 2020 (Period B), and after January 1, 2020, inclusive of impact from the COVID pandemic (Period C).

RESULTS

Reviewed were 11,819 elective TKAs and 10,212 elective THAs. RAPT scores were available for 6,759 TKA patients and 5,589 THA patients. For both TKA and THA, RAPT scores between IP, same-day, and next-day discharged OP were significantly different across all time periods (P < .001). The percentage of OP designation increased across all time periods for TKA and THA. Over these same time periods, mean RAPT scores decreased significantly for both OP TKA and OP THA (P < .01). Concurrent with these changes were significant increases in OP THA 90-day readmission rates across Periods A and B (P = .010) as well as A and C (P = .006). Readmitted OP TKA had significantly lower RAPT scores than OP TKA without readmission during Period B (P < .001). Readmitted OP THA had significantly lower RAPT scores than those without readmission for all periods (P < .05). To facilitate clinical utility, median RAPT scores were also analyzed, and showed that RAPT scores for OP THA patients with readmission were 1 to 2 points lower for all time periods.

CONCLUSION

RAPT scores correlate with IP versus OP status for both TKA and THA and vary significantly with same-day versus next-day discharge. OP TJA RAPT scores may also help predict readmission, and counsel some patients away from OP surgery. Average RAPT scores of 10, 9, and 8 appeared to be separators for same day, next day, and inpatient stay. Changes to the IPO and COVID pandemic correlate with decrease in RAPT scores for both TKA and THA patients within all designations. In addition, a shift toward lower RAPT for OP TJA correlates with increased 90-day readmission rates for OP TJA. Taken together, these results suggest that patients with poorer function and worse social support systems are increasingly being driven toward OP surgery by these changes, which may play a role in increasing readmission rates. Social support and functional factors should be considered for OP elective TKA and THA. Further, any OP TJA value-based payment system must account for these variables.

Ambulatory total hip arthroplasty: Causes for failure to launch and associated risk factors

Aims

The volume of ambulatory total hip arthroplasty (THA) procedures is increasing due to the emphasis on value-based care. The purpose of the study is to identify the causes for failed same-day discharge (SDD) and perioperative factors leading to failed SDD.

Methods

This retrospective cohort study followed pre-selected patients for SDD THA from 1 August 2018 to 31 December 2020. Inclusion criteria were patients undergoing unilateral THA with appropriate social support, age 18 to 75 years, and BMI < 37 kg/m². Patients with opioid dependence, coronary artery disease, and valvular heart disease were excluded. Demographics, comorbidities, and perioperative data were collected from the electronic medical records. Possible risk factors for failed SDD were identified using multivariate logistic regression.

Results

In all, 278 patients were identified with a mean age of 57.1 years (SD 8.1) and a mean BMI of 27.3 kg/m² (SD 4.5). A total of 96 patients failed SDD, with the most common reasons being failure to clear physical therapy (26%), dizziness (22%), and postoperative nausea and vomiting (11%). Risk factors associated with failed SDD included smokers (odds ratio (OR) 6.24; p = 0.009), a maximum postoperative pain score > 8 (OR 4.76; p = 0.004), and procedures starting after 11 am (OR 2.28; p = 0.015). A higher postoperative tolerable pain goal (numerical rating scale 4 to 10) was found to be associated with successful SDD (OR 2.7; p = 0.001). Age, BMI, surgical approach, American Society of Anesthesiologists grade, and anaesthesia type were not associated with failed SDD.

Conclusion

SDD is a safe and viable option for pre-selected patients interested in rapid recovery THA. The most common causes for failure to launch were failing to clear physical thereapy and patient symptomatology. Risk factors associated with failed SSD highlight the importance of preoperative counselling regarding smoking cessation and postoperative pain to set reasonable expectations. Future interventions should aim to improve patient postoperative mobilization, pain control, and decrease symptomatology.

Cite this article: Bone Jt Open 2022;3(9):684–691.

Artificial intelligence algorithms accurately predict prolonged length of stay following revision total knee arthroplasty

PURPOSE

Although the average length of hospital stay following revision total knee arthroplasty (TKA) has decreased over recent years due to improved perioperative and intraoperative techniques and planning, prolonged length of stay (LOS) continues to be a substantial driver of hospital costs. The purpose of this study was to develop and validate artificial intelligence algorithms for the prediction of prolonged length of stay for patients following revision TKA.

METHODS

A total of 2512 consecutive patients who underwent revision TKA were evaluated. Those patients with a length of stay greater than 75th percentile for all length of stays were defined as patients with prolonged LOS. Three artificial intelligence algorithms were developed to predict prolonged LOS following revision TKA and these models were assessed by discrimination, calibration and decision curve analysis.

RESULTS

The strongest predictors for prolonged length of stay following revision TKA were age (> 75 years; p < 0.001), Charlson Comorbidity Index (> 6; p < 0.001) and body mass index (> 35 kg/m²; p < 0.001). The three artificial intelligence algorithms all achieved excellent performance across discrimination (AUC > 0.84) and decision curve analysis (p < 0.01).

CONCLUSION

The study findings demonstrate excellent performance on discrimination, calibration and decision curve analysis for all three candidate algorithms. This highlights the potential of these artificial intelligence algorithms to assist in the preoperative identification of patients with an increased risk of prolonged LOS following revision TKA, which may aid in strategic discharge planning.

LEVEL OF EVIDENCE

IV.

Short-Stay Arthroplasty is Not Associated With Increased Risk of 90-Day Hospital Returns

BACKGROUND

With the removal of total hip arthroplasty (THA) and total knee arthroplasty (TKA) from the inpatient-only list, medical centers are faced with challenging transitions to outpatient surgery. We investigated if short-stay arthroplasty, defined as length of stay (LOS) <24 hours, would influence 90-day readmissions and emergency department (ED) visits at a tertiary referral center.

METHODS

The institutional database was retrospectively queried for primary TKAs and THAs from July 2015 to January 2018, resulting in 2,217 patients (1,361 TKA and 856 THA). Patient demographics, including age, gender, body mass index, and American Society of Anesthesiologists score were collected. LOS, disposition, cost of care, 90-day ED visits, and readmissions were identified through the institutional database using electronic medical record data. Univariable and multivariable models were used to evaluate rates of 90-day readmissions and ED visits based on LOS <24 hours vs ≥24 hours.

RESULTS

LOS <24 h was associated with significant decreases in 90-day ED visits (P = .003) and readmissions (P = .002). After controlling for potential confounding variables with a multivariable model, a significant decrease in ED visits (P = .034) remained in the THA cohort alone. Within TKA and THA cohorts, LOS <24 h was associated with lower costs (P < .001). Eighteen percent of patients with ≥24 h LOS were discharged to skilled nursing or rehabilitation facilities.

CONCLUSION

In this cohort, LOS <24 hours was associated with decreased 90-day readmissions, ED visits, and costs. With the goal of minimizing costs and maintaining patient safety while efficiently using resources, outpatient and short-stay arthroplasty are valuable, feasible options in tertiary academic centers.

Same-Day Outpatient Lower-Extremity Joint Replacement: A Critical Analysis Review

➢ The economics of transitioning total joint arthroplasty (TJA) to standalone ambulatory surgery centers (ASCs) should not be capitalized on at the expense of patient safety in the absence of established superior patient outcomes. ➢ Proper patient selection is essential to maximizing safety and avoiding complications resulting in readmission. ➢ Ambulatory TJA programs should focus on reducing complications frequently associated with delays in discharge. ➢ The transition from hospital-based TJA to ASC-based TJA has substantial financial implications for the hospital, payer, patient, and surgeon.

Increased Complications in Octogenarians Undergoing Same-Day Discharge following Total Knee Arthroplasty: A Matched Cohort Analysis

Same-day discharge pathways in total knee arthroplasty (TKA) are gaining popularity as a means to increase patient satisfaction and reduce overall costs, but these pathways have not been thoroughly evaluated in potentially at-risk populations, such as in patients ≥80 years old. The purpose of this study was to compare 90-day complications and mortality following same-day discharge after primary TKA in patients ≥80 years old and those <80 years old. Patients who underwent unilateral primary TKA, were discharged on postoperative day 0, and had a minimum 90-day follow-up were identified in a national insurance claims database (PearlDiver Technologies) using Current Procedural Terminology code 27447. These patients were stratified into two cohorts based upon age: (1) nonoctogenarians (<80 years old) and (2) octogenarians (≥80 years old). These cohorts were propensity matched based upon sex, Charlson comorbidity index, and obesity status. Univariate analysis was performed to determine differences in 90-day complications and mortality between the two cohorts. In total, 1,111 patients were included in each cohort. Both cohorts were successfully matched, with no observed differences in matched parameters for demographics or comorbidities. There was no significant difference in 90-day mortality between the two cohorts (p = 0.896). However, octogenarians were at significantly increased risk of postoperative atrial fibrillation (20.8 vs. 10.4%; p < 0.001), nonatrial fibrillation arrhythmias (8.4 vs. 5.6%; p = 0.009), pneumonia (4.5 vs. 2.2%; p = 0.002), stroke (3.1 vs. 1.7%; p = 0.037), heart failure (10.5 vs. 7.5%; p = 0.012), and urinary tract infection (UTI; 14.3 vs. 9.4%; p < 0.001) compared with the nonoctogenarian cohort. Relative to matched controls, octogenarians were at significantly increased risk of numerous 90-day medical complications following same-day primary TKA, including cardiopulmonary complications, stroke, and UTI. Clinicians should be cognizant of these complications and counsel patients appropriately when electing to perform same-day TKA in the octogenarian population.

A Novel Machine Learning Predictive Tool Assessing Outpatient or Inpatient Designation for Medicare Patients Undergoing Total Knee Arthroplasty

Background

Methods

Results

Conclusions

Coding Variation and Adherence to Methodological Standards in Cardiac Research Using the National Inpatient Sample

Background: Code selection is crucial to the accuracy and reproducibility of studies using administrative data, however a comprehensive assessment of coding trends for major cardiac diagnoses and procedures is lacking. We aimed to evaluate trends in administrative code utilization for major cardiac diagnoses and procedures, and adherence to required methodological practices in cardiac research using the National Inpatient Sample (NIS).

Methods: In this observational study of 445 articles, ICD-9-CM codes corresponding to acute myocardial infarction (AMI), heart failure, atrial fibrillation, percutaneous coronary intervention, and coronary artery bypass grafting were collected and analyzed. The NIS was used to compare the number of hospitalizations between the most frequently encountered AMI case definitions. Key elements were abstracted from each article to evaluate adherence to required methodological practices.

Results: Variation in code utilization was observed for each diagnosis and procedure assessed, and the number of unique case definitions published per year increased throughout the study period (P < 0.001), driven largely by the significant increase in articles per year (P < 0.001). Off-target codes were observed in 39 (8.8%) studies. Upon reintroduction into the NIS for 2008–2012, the most commonly encountered case definitions for AMI were found to yield significantly different estimates of AMI hospitalizations and hospitalization trends over time. Three hundred and ninety-nine articles (84%) did not adhere to one or more required research practices. Overall adherence was superior for publications in higher-impact journals (P = 0.002).

Conclusions: Substantial variation in code selection exists for major cardiac diagnoses and procedures, and non-adherence to methodological standards is widespread. These data have important implications for the accuracy and generalizability of analyses using the NIS.

Abnormal Coagulation as a Risk Factor for Postoperative Complications After Primary and Revision Total Hip and Total Knee Arthroplasty

BACKGROUND

Patients undergoing total joint arthroplasty (TJA) have an increased likelihood of having an abnormal coagulation profile compared with the general population. Coagulation abnormalities are often screened for before surgery and considered during perioperative planning. This study assesses a preoperative abnormal coagulation profile as a risk factor for postoperative complications after total hip arthroplasty (THA), revision THA (rTHA), total knee arthroplasty (TKA), and revision TKA (rTKA) and then examines specific coagulopathies to determine their influence on complication rates.

METHODS

Patients who underwent THA, rTHA, TKA, or rTKA from 2011 to 2017 were identified in the American College of Surgeons National Surgical Quality Improvement Program database and then assessed for preoperative abnormal coagulation profiles. Various postoperative complications were analyzed for each cohort, and two separate multivariate regression analyses were used to assess the relationship between abnormal coagulation and postoperative complications.

RESULTS

403,566 THA, rTHA, TKA, or rTKA cases were identified, and 40,466 (10.0%) of patients were found to have an abnormal coagulation profile. Patients with preoperative coagulation abnormalities had higher likelihoods of postoperative complications after primary TJA than in revision TJA. An international normalized ratio>1.2 was associated with the most types of postoperative complications, followed by a bleeding disorder diagnosis. A partial thromboplastin time>35 seconds was associated with only one type of postoperative complication, while a platelet count <150,000 per μL was associated with postoperative complications only after TKA.

CONCLUSION

TJA in patients with abnormal coagulation profiles may result in adverse outcomes. These patients may benefit from preoperative intervention. Prophylactic care needs to be personalized to the specific coagulation abnormalities present.

A Novel Scoring System to Predict Length of Stay After Anterior Cervical Discectomy and Fusion

INTRODUCTION

The movement toward reducing healthcare expenditures has led to an increased volume of outpatient anterior cervical diskectomy and fusions (ACDFs). Appropriateness for outpatient surgery can be gauged based on the duration of recovery each patient will likely need.

METHODS

Patients undergoing 1- or 2-level ACDFs were retrospectively identified at a single Level I spine surgery referral institution. Length of stay (LOS) was categorized binarily as either less than two midnights or two or more midnights. The data were split into training (80%) and test (20%) sets. Two multivariate regressions and three machine learning models were developed to predict a probability of LOS ≥ 2 based on preoperative patient characteristics. Using each model, coefficients were computed for each risk factor based on the training data set and used to create a calculatable ACDF Predictive Scoring System (APSS). Performance of each APSS was then evaluated on a subsample of the data set withheld from training. Decision curve analysis was done to evaluate benefit across probability thresholds for the best performing model.

RESULTS

In the final analysis, 1,516 patients had a LOS <2 and 643 had a LOS ≥2. Patient characteristics used for predictive modeling were American Society of Anesthesiologists score, age, body mass index, sex, procedure type, history of chronic pulmonary disease, depression, diabetes, hypertension, and hypothyroidism. The best performing APSS was modeled after a lasso regression. When applied to the withheld test data set, the APSS-lasso had an area under the curve from the receiver operating characteristic curve of 0.68, with a specificity of 0.78 and a sensitivity of 0.49. The calculated APSS scores ranged between 0 and 45 and corresponded to a probability of LOS ≥2 between 4% and 97%.

CONCLUSION

Using classic statistics and machine learning, this scoring system provides a platform for stratifying patients undergoing ACDF into an inpatient or outpatient surgical setting.

Is Conversion TKA a Primary or Revision? Clinical Course and Complication Risks Approximating Revision TKA Rather Than Primary TKA

BACKGROUND

Conversion total knee arthroplasty (convTKA) is associated with increased resource utilization and costs compared with primary TKA. The purpose of this study is to compare 1) surgical time, 2) hospitalization length (LOS), 3) complications, 4) infection, and 5) readmissions in patients undergoing convTKA to both primary TKA and revision TKA patients.

METHODS

The American College of Surgeons National Surgical Quality Improvement Project database was queried from 2008 to 2018. Patients undergoing convTKA (n = 1,665, 0.5%) were defined by selecting Current Procedural Terminology codes 27,447 and 20,680. We compared the outcomes of interest to patients undergoing primary TKA (n = 348,624) and to patients undergoing aseptic revision TKA (n = 8213). Univariate and multivariate logistic regression was performed to identify the relative risk of postoperative complications.

RESULTS

Compared with patients undergoing primary TKA, convTKA patients were younger (P < .001), had lower body mass index (P < .001), and were less likely to be American Society of Anesthesiologist class III/IV (P < .001). These patients had significantly longer operative times (122.6 vs 90.3 min, P < .001), increased LOS (P < .001), increased risks for any complication (OR 1.94), surgical site infection (OR 1.84), reoperation (OR 2.18), and readmissions (OR 1.60) after controlling for confounders. Compared with aseptic TKA revisions, operative times were shorter (122.6 vs 148.2 min, P < .001), but LOS (2.91 vs 2.95 days, P = .698) was similar. Furthermore, relative risk for any complication (P = .350), surgical site infection (P = .964), reoperation (P = .296), and readmissions (P = .844) did not differ.

CONCLUSION

Conversion TKA procedures share more similarities with revision TKA rather than primary TKA procedures. Without a distinct procedural and diagnosis-related group, there are financial disincentives to care for these complex patients.

LEVEL OF EVIDENCE

II.

Pain associated with cemented and uncemented long-stemmed tibial components in revision total knee arthroplasty

AIMS

Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components.

METHODS

This is a retrospective cohort study involving 110 patients with revision TKA with cemented versus uncemented stemmed tibial components. Patients who underwent revision TKA with stemmed tibial components over a 15-year period at a single institution with at least two-year follow-up were assessed. Pain was evaluated through postal surveys. There were 63 patients with cemented tibial stems and 47 with uncemented stems. Radiographs and Knee Society Scores were used to evaluate for objective findings associated with pain or patient dissatisfaction. Postal surveys were analyzed using Fisher's exact test and the independent-samples t-test. Logistic regression was used to adjust for age, sex, and preoperative bone loss.

RESULTS

No statistically significant differences in stem length, operative side, or indications for revision were found between the two cohorts. Tibial pain at the end of the stem was present in 25.3% (16/63) of cemented stems and 25.5% (12/47) of uncemented stems (p = 1.000); 74.6% (47/63) of cemented patients and 78.7% (37/47) of uncemented patients were satisfied following revision TKA (p = 0.657).

CONCLUSION

There were no differences in patient satisfaction, overall pain, and diaphyseal tibial pain in cemented and uncemented stemmed tibial components in revision TKA. Patient factors, rather than implant selection and surgical technique, likely play a large role in the presence of postoperative pain. Stemmed tibial components have been shown to be a possible source of pain in revision TKA. There is no difference in patient satisfaction or postoperative pain with cemented or uncemented stemmed tibial components in revision TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):165-170.

A Novel Machine Learning Predictive Tool Assessing Outpatient or Inpatient Designation for Medicare Patients Undergoing Total Hip Arthroplasty

Background

The Centers for Medicare and Medicaid Services removed total hip arthroplasty (THA) from the inpatient-only list. This has created significant confusion regarding which patients qualify for an inpatient designation. The purpose of this study is to develop and validate a novel predictive tool for preoperatively objectively determining “outpatient” vs “inpatient” status for THA in the Medicare population.

Methods

A cohort of Medicare patients undergoing primary THA between January 2017 and September 2019 was retrospectively reviewed. A machine learning model was trained using 80% of the THA patients, and the remaining 20% was used for testing the model performance in terms of accuracy and the average area under the receiver operating characteristic curve. Feature importance was obtained for each feature used in the model.

Results

One thousand ninety-one patients had outpatient stays, and 318 qualified for inpatient designation. Significant associations were demonstrated between inpatient designations and the following: higher BMI, increased patient age, better preoperative functional scores, higher American Society of Anesthesiologist Physical Status Classification, higher Modified Frailty Index, higher Charlson Comorbidity Index, female gender, and numerous comorbidities. The XGBoost model for predicting an inpatient or outpatient stay was 78.7% accurate with the area under the receiver operating characteristic curve to be 81.5%.

Conclusions

Using readily available key baseline characteristics, functional scores and comorbidities, this machine-learning model accurately predicts an “outpatient” or “inpatient” stay after THA in the Medicare population. BMI, age, functional scores, and American Society of Anesthesiologist Physical Status Classification had the highest influence on this predictive model.

Free Falling: Declining Inflation-Adjusted Payment for Arthroplasty Surgeons

BACKGROUND

Over the past decade, there have been ongoing concerns over declining surgeon compensation for lower extremity arthroplasty. We aimed to determine changes in surgeon payment, patient charges, and overall reimbursement rates for patients undergoing unicompartmental arthroplasty (UKA) and both primary and revision total knee (TKA) and hip (THA) arthroplasty.

METHODS

Using Medicare data from 2012 to 2017, we determined inflation-adjusted changes in annual surgeon payment (professional fee), patient charges, and reimbursement rate (payment-to-charge ratio) for UKA and primary/revision TKA and THA. Both nonweighted and weighted (by procedure frequency/volume) means were calculated.

RESULTS

Inflation-adjusted surgeon payment decreased for all procedures analyzed, with primary TKA (-17%) and THA (-11%) falling the most. Payment for UKA increased the most (+30%). There was a small increase in charges for THA revision (+2.2%, +2.1%, and +3.2% for acetabulum only, femur only, and both components, respectively). Charges for primary TKA (-3.7%) and THA (-1.5%) decreased slightly. The reimbursement rate for all procedures fell with UKA (-15%), TKA (-14%), and THA (-10%) falling the most. After weighting by procedure frequency/volume and combining all surgeries, average charges fell slightly (-0.7%), whereas surgeon payment (-13%) and reimbursement rate (-12%) fell more sharply.

CONCLUSION

Although patient charges have grown in pace with the inflationary rate for primary and revision TKA and THA, surgeon payment and reimbursement rates have fallen sharply. The orthopedic community needs to be aware of these financial trends to communicate to payers and health care policy makers the importance of protecting a sustainable payment infrastructure.

Medicare Total Knee Arthroplasty Patients Need Not Stay 2 Midnights for Full Facility Reimbursement

BACKGROUND

Health care systems are concerned that facility reimbursements will be reduced based on patient length of stay (LOS) of <2 midnights with the removal of total knee arthroplasty (TKA) from the inpatient-only list. The purpose of this study was to evaluate the effect of LOS and postdischarge disposition on facility reimbursement.

METHODS

We evaluated a consecutive series of 470 primary Medicare TKA patients performed at a single institution from 2018 to 2019. We analyzed facility reimbursement based on patient LOS and discharge disposition. Descriptive statistics were analyzed using chi-square test, analysis of variance, and Student t test calculations.

RESULTS

Overall, the facility was fully reimbursed in 401 patients (85%) at a mean of $11,169. The facility received full reimbursement for 323 of 326 (99%) patients with an LOS of <2 midnights who were discharged to home at a mean of $11,156. This reimbursement was significantly (P < .001) higher than patients who had an LOS <2 midnights who were discharged with home health (mean, $9773) or to a facility (mean, $10,095). For those with LOS >2 midnights, there was no difference in mean reimbursement among discharge dispositions ($11,202 vs $11,249 vs $11,085, P = .65).

CONCLUSION

In this study, Medicare TKA patients with LOS <2 midnights were fully reimbursed 99% of the time as an inpatient as long as they are discharged to home without home health or to a rehabilitation facility. Those discharged before 2 midnights who require home health service or inpatient facility are more likely to be reimbursed at a lower penalized rate.

Clinical, functional and radiographic outcomes of primary total hip arthroplasty between direct anterior approach and posterior approach: a systematic review and meta-analysis

BACKGROUND

The purpose of this systematic review and meta-analysis was to compare the direct anterior approach and posterior approach for primary total hip arthroplasty in terms of the clinical, functional and radiographic outcomes.

METHODS

We searched the PubMed and EMBASE databases and Cochrane Library from their inception to November 1, 2019. We searched for previously published articles and meta-analyses of randomized controlled trials.

RESULTS

A total of 7 randomized controlled trials with 600 participants met the inclusion criteria. Among these patients, 301 and 299 were included in the DAA and PA groups, respectively. The DAA was associated with a longer surgery by a mean duration of 13.74 min (95% CI 6.88 to 20.61, p < 0.0001, I2 = 93%). The postoperative early functional outcomes were significantly better in the DAA group than in the PA group, such as the Visual Analogue Scale (VAS) score at 1 day postoperatively (MD = -0.65, 95% CI - 0.91 to - 0.38, p < 0.00001, I2 = 0%), VAS score at 2 days postoperatively (MD = -0.67, 95% CI - 1.34 to - 0.01, p = 0.05, I2 = 88%) and Harris Hip Score (HHS) at 6 weeks postoperatively (MD = 6.05, 95% CI 1.14 to 10.95, p = 0.02, I2 = 52%). There was no significant difference between the DAA and PA groups in the length of the incision, hospital length of stay (LOS), blood loss, transfusion rates or complication rates. We found no significant difference between the two groups regarding late functional outcomes, such as the VAS score at 12 months postoperatively or the HHS scores at 3, 6, and 12 months postoperatively. A significant difference in the radiographic outcomes was not detected.

CONCLUSIONS

The DAA requires a longer surgery time than does the PA in primary total hip arthroplasty. The DAA yields better early functional recovery than does the PA. There was no significant difference between the two groups in terms of other clinical, complication-related, late functional or radiographic outcomes. The evidence on the superiority of the DAA is insufficient and needs to be studied further.

The Financial Implications of the Removal of Total Knee Arthroplasty From the Medicare Inpatient-Only List

BACKGROUND

Centers for Medicare and Medicaid Services removed total knee arthroplasties (TKAs) from the Inpatient-Only list on January 1, 2018, which meant TKAs could be performed on a hospital outpatient basis. We sought to understand (1) what the financial implications have been for hospitals, (2) to what extent financial incentives have influenced the adoption of outpatient TKAs across hospitals, (3) whether adoption of outpatient TKAs has impacted the success of hospitals with managing post-acute care (PAC) spend, and (4) the financial implications to Medicare of the adoption of outpatient TKAs.

METHODS

We used national patient-level Medicare fee-for-service Part A claims data (100% sample) from January 2018 through June 2019 to calculate the inpatient and outpatient TKA payment rate for each hospital, and the distribution in these payments across the country. We then ran case-level regressions to understand the factors associated with adoption of outpatient TKAs, and the drivers of PAC spend. Finally, we quantified the savings to Medicare.

RESULTS

Hospitals on average received $3682 (30%) lower payment from Medicare for outpatient TKA cases, but this varied widely across hospitals. The difference in payment rates across hospitals was not statistically significantly related to their adoption rate of outpatient TKAs. PAC spend was higher for same-day discharges, but lower for cases that stayed at least 1 night. Based on the adoption rate of outpatient TKAs in Q2 2019, Medicare saved $355M on a run rate basis.

CONCLUSION

Hospitals have adopted outpatient TKAs independent of the financial impact. Medicare has benefited from lower PAC spend and lower payments to hospitals.

Total Knee Replacement: The Inpatient-Only List and the Two Midnight Rule, Patient Impact, Length of Stay, Compliance Solutions, Audits, and Economic Consequences

BACKGROUND

In November 2017, CMS finalized the 2018 Medicare Outpatient Prospective Payment System rule that removed TKA from the Medicare inpatient-only (IPO) list. This action had significant and unexpected consequences.

METHODS

We looked at 3 levels of the IPO rule impact on TKA for Medicare beneficiaries: a national comparison of FFS inpatient and outpatient classification for 2017 vs 2018; a survey of AAHKS surgeons completed in April 2019; and an in-depth analysis of a large academic medical center experience. An analysis of change in admission classification of patients with TKA over time, number of QIO audits, compliance solutions for the new rule, and cost implications of those compliance solutions were evaluated.

RESULTS

Hospital reimbursement averages $10,122 in an outpatient facility but does not include the physician payment. Average hospital reimbursement in the inpatient setting is $11,760. The difference in hospital reimbursement varies widely (90th percentile decrease, $6725 vs 10th percentile $2048). Physician payments are the same in both settings (avg $1403). Patients with TKA not designated for inpatient admissions are not eligible for bundle payment programs. Patients designated as outpatients are subjected to higher out-of-pocket expenses. Patients may have an annual Medicare Part B Deductible ($185) and a 20% copay as well as prescription and durable medical equipment costs. An AAHKS survey demonstrated that 45.08% were with inpatient designation only, 17.62% were with outpatient designation only, 25.39% were designated as necessary, and 10.1% were designated by the hospital. This survey showed that 66 of 374 (17.65%) patients had undergone a QIO audit as a result of issues with the IPO rule. An evaluation of an AMC demonstrated that since January 1, 2018, 470 of 690 (68.1%) of CMS patients with TKA left in less than 2 midnights. The institution was subjected to 2 QIO audits.

CONCLUSIONS

There are many unintended consequences to the IPO rule application to TKA.