Why are Inpatient THA / TKA Readmissions and Complications Increasing?


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This article is part of the Dexur Insight, which is focused on Hospital Quality and Safety topics and is read by CEOs, CMOs, CNOs, CQOs, Quality, Safety, Compliance, Analytics & Performance teams. Please email dexurqualitysights@dexur5.com to join this newsletter and receive updates (not more than once per week).

Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) are critical measures in assessing the quality of care provided by healthcare facilities, particularly in the context of Medicare's value-based care models. These procedures are common among the elderly population, who are the primary beneficiaries of Medicare. The rates of 30-day readmission and complications after THA/TKA are significant indicators of the quality and effectiveness of perioperative care, postoperative management, and the overall health system's ability to provide coordinated care. These metrics directly impact various Centers for Medicare & Medicaid Services (CMS) Quality Programs, such as CMS Star Rating and the Hospital Readmissions Reduction Program (HRRP), which penalizes hospitals with higher than expected readmission rates for certain conditions and procedures, including THA/TKA.

The below table presents a concerning trend in the outcomes of Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) procedures over three CMS Reporting periods, from 2017 to 2024. Notably, the THA/TKA 30-day readmission rate has shown a gradual decrease from 2017 to 2021 (4.6% in 2017 to 4% in 2020) and then a gradual increase from 4.0% in 2022 to 4.3% in 2024. Similarly, for THA/TKA complications, there has been a gradual decrease from 2017 to 2020 (3% in 2017 to 2.4% in 2021) and then a gradual increase from 2.4% in 2022 to 3.2% in 2024. Contrastingly, Dexur’s data for readmissions and complications for other conditions like Acute Myocardial Infarction (AMI), Heart Failure (HF), and Chronic Obstructive Pulmonary Disease (COPD) show a declining trend in these measures.

CMS Reporting Period 2017 2018 2019 2020 2021 2022 2023 2024
THA/TKA 30-Day Readmission Rate 4.6 4.4 4.2 4.0 4.0 4.0 4.1 4.3
Complication Rate After THA/TKA 3 2.8 2.6 2.5 2.4 2.4 2.4 3.2
Change in All Inpatient Hospitalizations from 2017 NA 19% 0% -2% -1% -21% 12% -9%
Change in THA/TKA Index Inpatient Population for THA/TKA Readmissions from 2017 NA 6% 3% 1% -4% -22% -28% -39%
Change in THA/TKA Index Inpatient Population for THA/TKA Complications from 2017 NA 6% 3% 2% -3% -18% -32% -38%

What Could Be the Underlying Cause Behind This Trend?

The underlying trend of increasing readmission and complication rates for Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) may be partially attributed to the significant shift from inpatient to outpatient surgeries. This transition has been facilitated by advancements in surgical techniques, anesthesia, and pain management, allowing patients to recover at home sooner than in the past. Dexur's 2017 analysis highlighted a critical shift in the landscape of joint replacement surgeries, particularly noting that 57.5% of TKA cases could be transitioned to outpatient settings under new CMS guidelines. Effective January 1, 2018, TKA was removed from the inpatient-only (IPO) list, marking a significant policy change by the Department of Health and Human Services.

This is reflected in the data in the above table, where the Initial Index Inpatient Population for THA/TKA Readmissions and Complications for the Traditional Medicare Fee For Service (FFS) population has decreased gradually since 2017. In 2024, We see a significant change of 38% and 39% compared to 2023. However, the overall Traditional Medicare (FFS) inpatient population has decreased only by 9%. This supports the hypothesis of changing THA/TKA population shifts from Inpatient to Outpatient.

The observed trend of increasing readmission and complication rates for Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) procedures, in the context of the shift from inpatient to outpatient settings, can be analyzed through the lens of patient selection criteria. The hypothesis that patients transitioning from inpatient to outpatient surgeries may be healthier, while those remaining for inpatient procedures could be sicker, and hence more prone to worse outcomes, is supported by various research findings and healthcare analyses.

Patients undergoing surgeries in outpatient settings are typically selected based on stringent criteria that ensure they are of lower risk. These criteria often include factors such as overall physical health, the absence of significant comorbidities, and a supportive home environment conducive to recovery. As a result, these patients are less likely to experience complications or require readmission due to their healthier baseline status and the lower complexity of their medical needs.

Conversely, patients who continue to receive care in an inpatient setting are often those with more significant health issues, including higher comorbidity burdens or poorer preoperative health statuses. These factors inherently increase their risk of postoperative complications and readmissions. Research has consistently shown that patients with higher comorbidity indices are at an increased risk of adverse outcomes post-surgery.

What this may mean for Hospitals?

For hospitals that have rapidly transitioned to outpatient procedures for Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA), this shift may have unintended consequences on the profile of their inpatient population. Specifically, these hospitals might observe a concentration of significantly sicker inpatients who are at a higher risk of readmissions and complications post-surgery. This change arises because the healthier patient cohort, who previously would have been part of the inpatient surgery demographic, is now being treated in an outpatient setting. Consequently, the remaining inpatient group is skewed towards those with more complex health issues and higher risks, potentially leading to poorer overall outcomes for this group.

A critical challenge in this scenario is the accurate capture of the patient's full risk profile through medical coding. If the coding does not adequately reflect the complexity and severity of patients' conditions, hospitals might face discrepancies in their reported outcomes versus the actual risk-adjusted expectations. This discrepancy can have significant implications, not only for patient care but also for hospital performance metrics, reimbursement rates, and standings in various quality programs administered by healthcare authorities like CMS.

Dexur’s analysis, particularly the Observed Vs Risk Adjusted Gap analysis, becomes a pivotal tool for hospitals in this context. By examining the underlying incidence rates of each risk factor associated with THA/TKA measures, hospitals can gain a clearer understanding of how their patient demographics are shifting and what impact this may have on surgical outcomes. This analysis helps hospitals identify if they are experiencing an apparent increase in readmission and complication rates due to a sicker inpatient population or if there are gaps in their medical coding practices that fail to capture the full scope of patient risk.

Understanding these dynamics is crucial for hospitals to adapt their strategies. It may necessitate a reevaluation of preoperative assessments, postoperative care protocols, and the overall approach to patient management, ensuring that the care provided is aligned with the increased complexity of the inpatient population. Furthermore, accurate medical coding becomes paramount in ensuring that the hospital's reported metrics accurately reflect the patient population's risk profile, enabling better performance under quality programs and ensuring appropriate reimbursement.