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    Why Are Some Patients Poor Candidates for Outpatient THA?

    Dr. Patawut Bovonratwet and Dr. Michael Ast answer ICJR’s questions about their study using the NSQIP database to evaluate the 30-day readmission rate following outpatient primary total hip arthroplasty, as well as the risk factors contributing to readmission.

    ICJR: What questions did you and your co-authors want to answer with this study?

    Patawut Bovonratwet, MD: Three key questions about outcomes of outpatient primary total hip arthroplasty (THA) were addressed in this study:

    • What are the incidence, timing, and common reasons for 30-day readmission after patients who underwent outpatient THA?
    • What are the risk factors for occurrence of 30-day readmission in these patients?
    • Would patients at high risk for 30-day readmission benefit from a traditional inpatient stay?

    ICJR: What did you conclude?

    Dr. Bovonratwet: Utilizing data from the National Surgical Quality Improvement Program (NSQIP) database, we found that overall, patients undergoing outpatient THA have a low rate of 30-day readmission. Of course, some patients will have a higher risk, and in this study, older age and presence of a bleeding disorder were found to be risk factors for 30-day readmission after outpatient THA.

    Patients older than age 75 demonstrated the most clinically significant risk for subsequent medically related 30-day readmission, which was reduced if they had stayed overnight after the procedure. Patients in this age group, therefore, may not be appropriate candidates for outpatient THA.

    RELATED: Outpatient Primary Direct Anterior Total Hip Arthroplasty, an ICJR Featured Surgery

    ICJR: How did you reach your conclusions? What was your study cohort and what did you find with your analysis?

    Dr. Bovonratwet: Our study cohort consisted of 5245 patients from the NSQIP database who had undergone outpatient THA (defined as length of stay equal to 0 days) in 2012 through 2018. Briefly, the NSQIP database contains more than 150 perioperative variables from more than 500 participating institutions in the US. Trained clinical and surgical reviewers record patient data through the 30th postoperative day, regardless of the discharge date.

    The incidence of 30-day readmission after outpatient THA was 1.6% in this study, with an average time from surgery to readmission of approximately 2 weeks. The majority of readmissions were for surgically related (62%) rather than medically related (38%) reasons. As mentioned above, the risk factors for 30-day readmission after outpatient THA included older age relative to 18 to 60 years old (most notably 71 to 75 years old, relative risk [RR]=2.3; 76 to 80 years old, RR=6.6; and more than 80 years old, RR=5.6; P<0.001) and bleeding disorders (RR=4.5; P=0.010).

    The risk of 30-day medically related readmission in older patients can be reduced by having them stay in the hospital after THA. In this study, patients age 76 to 80 and those over age 80 were found to have a reduced risks of 30-day medically related readmission if they stayed 1 night at the hospital (RR=0.3 and RR=0.2, respectively).

    ICJR: Why are these findings significant for clinical practice?

    Michael P. Ast, MD: A higher volume of outpatient primary THAs is starting to be performed due to touted benefits such as reduced costs and increased patient satisfaction. In the past 18 months, the Covid-19 pandemic has accelerated the move to outpatient THA, as has removal of primary THA from the Centers for Medicare and Medicaid Services’ Inpatient-Only list for Medicare recipients.

    However, data on appropriate patient selection for this surgical protocol are scarce. Our study was able to identify patients who may be at high risk for 30-day readmission and thus may not be candidates for outpatient THA. This information can be used by surgeons to facilitate appropriate patient selection and assist with counseling patients about outpatient THA pathways. 

    Sources

    Bovonratwet P, Chen A, Shen TS, Ondeck N, Islam W, Ast MP, Su EP. What are the reasons and risk factors for 30-day readmission after outpatient total hip arthroplasty? (Paper 673) Presented at the 2021 Annual Meeting of the American Academy of Orthopaedic Surgeons, August 31-September 3, San Diego, California.

    Bovonratwet P, Chen AZ, Shen TS, et al. What are the reasons and risk factors for 30-day readmission after outpatient total hip arthroplasty? J Arthroplasty. 2021 Jul;36(7S):S258-S263.e1. doi: 10.1016/j.arth.2020.10.011. Epub 2020 Oct 15.

    About the Experts

    Patawut Bovonratwet, MD, is an orthopaedic surgery resident at Hospital for Special Surgery, New York, New York. Michael P. Ast, MD, is an Assistant Professor of Orthopaedic Surgery, specializing in adult reconstruction and joint replacement, at Hospital for Special Surgery, New York, New York. He is also the Chief Medical Innovation Officer and Vice Chair, Innovation, at Hospital for Special Surgery.

    Disclosures: Dr. Bovonratwet has no disclosures relevant to this article. Dr. Ast has disclosed that he receives royalties from, has stock or stock options in, is paid consultant for, and is a paid presenter or speaker for OrthAlign; that he has stock or stock options in HS2, OssoVR, and Parvizi Surgical Innovations; that he is a paid consultant for BD, ConformMIS, and Surgical Care Affiliates; that he is a paid consultant for, a paid presenter or speaker for, and receives research support from Smith & Nephew; and that he is a paid consultant for and a paid presenter or speaker for Stryker.