Total hip replacement has been shown to be a highly effective procedure for reducing pain and improving function among patients with disabling arthritis of the hip. However, the success of the procedure varies on the basis of a number of factors related to the patient (e.g., age, activity level, and comorbid conditions), the surgeon (e.g., specialty training, surgical technique, and volume of procedures performed), the hospital (e.g., implementation of standardized clinical care pathways, availability of dedicated staff, and volume of procedures performed), and the implant used (e.g., long-term survivorship). In this article, Katz et al. use administrative data to identify factors that are associated with an increased risk of revision during the first twelve years following primary total hip replacement in Medicare patients.
Their analysis is elegant, placing the risk of revision total hip replacement in the context of mortality for the Medicare population. This study has several important implications, particularly regarding the relative importance of interventions that reduce the long-term risk of revision total hip replacement (e.g., enhancements in implant longevity) versus those that result in a reduction in the short-term risk of revision total hip replacement (e.g., implementation of standardized clinical care pathways). Historically, much emphasis has been placed on strategies to improve the long-term survivorship of total hip replacement implants, including evolution in bearings and implant fixation. Katz et al., however, argue that, for the Medicare population, greater emphasis should be placed on reducing failures that occur within eighteen months of surgery, when the risk of revision is two times higher than during the subsequent decade. Furthermore, since the risk of dying over the twelve-year period following total hip replacement far exceeded the risk of revision surgery, especially among patients over seventy-five years old, for whom the risk of death was tenfold greater than the risk of revision, improving long-term implant survivorship may not be as relevant a goal in Medicare patients, who make up the majority of patients who have total hip replacement in the United States.
The authors appropriately state the limitations of their administrative dataset, which was based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes used for inpatient procedures. Yet it is important for readers to appreciate the evolution and expansion of administrative data available for use in health services research and policy over the past fifteen years. For example, the Centers for Medicare and Medicaid Services capture not only administrative data related to inpatient procedures but also encounters with outpatient care and clinics. The Current Procedural Terminology codes and Healthcare Common Procedure Coding System codes used in physician office administrative claims provide additional nuanced information about patient care (such as procedure laterality) that are not captured in ICD-9 codes. Furthermore, with the Medicare Prescription Drug, Improvement, and Modernization Act enacted by Congress in 2003, a wealth of pharmacological data is now captured for Medicare beneficiaries. Finally, with the U.S. Department of Health and Human Services mandating the transition from ICD-9-CM to ICD-10 codes in October 2014, a much greater level of detail will be available in the future with inpatient administrative data, including the laterality of total joint replacements.
The definition of administrative claims blurs even further in the context of a managed care plan that can link administrative claims with a patient’s electronic medical record. The breadth and complexity of administrative data have evolved considerably over the past fifteen years, as have the statistical methods to evaluate them. These trends point to increasing relevance of administrative claims data to orthopaedic research in the future, rather than a diminished role. There is much that remains to be discovered in administrative claims analysis of orthopaedic procedures. This elegant study by Katz et al. is the tip of the iceberg in terms of what can be achieved with even a subset of hospital-based administrative claims for a nationally representative population of patients managed with total joint replacement.
Previous authors, including Katz et al.1, have demonstrated a correlation between surgeon procedure volume and total hip replacement revision rates. In the current study, they found that differences in revision rates between high and low-volume surgeons occur during the first eighteen months following surgery, but not thereafter. This suggests that strategies to improve patient outcomes after total hip replacement should emphasize standardized clinical care pathways and systems-based care that are common among high-volume surgeons in high-volume hospitals over enhancements in implant longevity.
In the discussion, the authors claim that joint replacement registries, such as the American Joint Replacement Registry, are more suitable for assessing and optimizing outcomes in younger patients who are more likely to live long enough to face possible revision surgery. This assumption appears to be based on their belief that the primary purpose of joint replacement registries is to evaluate long-term implant survivorship. However, as has been shown in Scandinavian countries, Australia, and the United Kingdom, joint replacement registries are powerful tools for improving both short and long-term outcomes after total hip replacement by identifying patient, surgeon, hospital or health system, and implant-related factors that are associated with both positive and negative outcomes following total hip replacement2,3.
The U.S. health-care system is going through a period of unprecedented change and faces many challenges in the years ahead. Total joint replacements constitute the highest single procedural expense in the Medicare budget, due to many factors, including an increase in procedure rates and the adoption of newer, more expensive implant technologies. Total hip replacement implants have evolved over the past forty years, adding substantial cost to total hip replacement procedures. Some of these changes in implant technology have resulted in improvements in patient outcomes; others have not. Given that most of the growth in total hip replacement procedures over the next several decades is expected in the Medicare population, the findings of Katz et al. suggest that the orthopaedic community should shift its emphasis from developing new implant technologies to identifying best practices and systems of care that will help surgeons and health systems to provide high-quality, affordable care to their elderly patients with hip arthritis.