Which Patients Are at Greatest Risk for Readmission after THA?

    A recently published multi-center study provides guidance on modifiable risk factors orthopaedic surgeons can address prior to surgery to reduce the chances of patients being readmitted following total hip arthroplasty.


    Ryan Roach, MD, and Ajit Deshmukh, MD


    Paxton EW, Inacio MCS, Singh JA, Love R, Bini SA, Namba RS. Are there modifiable risk factors for hospital readmission after total hip arthroplasty in a US healthcare system? Clin Orthop Relat Res 2015 Apr 7. [Epub ahead of print]


    Much of the current literature regarding rates and risk factors for readmission following total joint arthroplasty is based on single-center studies, which limits application to larger populations.

    In this study, Paxton et al sought to investigate rates and risks factors for readmission in a large, multi-center health care system. Three important questions were posed:

    • What is the incidence of hospital readmission after primary THA
    • What are the reasons for readmission
    • What are the risk factors for readmission?

    To answer these questions, the researchers utilized the Kaiser Permanente Total Joint Replacement Registry. A total of 12,030 patients operated on by 176 different surgeons in 32 different hospitals were included. Data were collected in a prospective fashion.

    A 3.6% readmission rate was observed. The readmission rate in patients aged 65 years and older was 4.6%.

    The most common reasons for readmission were infection and inflammatory reaction resulting from internal joint prosthesis, other postoperative infection, unspecified septicemia, dislocation of the prosthetic joint and hematoma.

    After adjusting for all other variables, it was found that patient risk of 30-day readmission was associated with:

    • Age
    • Sex (male)
    • Race (black)
    • BMI (>35Kg/m2)
    • Surgeon volume (high)
    • Hospital volume (low)
    • Discharge disposition (other than home)
    • Medical complications
    • Length of stay (LOS) at the index procedure (>4 days)
    • Certain comorbidities

    Male patients had a 51% higher chance of readmission than women. Black patients were 26% more likely to be readmitted than white patients. Obese patients carried a 32% higher likelihood of readmission than non-obese patients, and morbidly obese patients had a 74% higher likelihood of readmission than non-obese patients.

    Patients operated on by medium-volume surgeons had a 35% lower likelihood of readmission than those operated on by high-volume surgeons; patients of low-volume compared with high-volume surgeons were found not to have a difference in readmission. Patients who had surgery performed at lower-volume hospitals had a 41% higher risk of readmission, and those at medium-volume had a 81% higher risk of readmission than those at high-volume hospitals.

    Patients with medical complications at the time of the index THA had a 180% higher risk of readmission, and those discharged to other facilities instead of home had a 89% higher likelihood of readmission. Patients with a LOS of 5 or more days were 80% more likely to be readmitted than those with a LOS of 3 days. Patients with pulmonary circulation disease, chronic pulmonary disease, hypothyroidism, or psychoses had a higher likelihood of readmission.

    Clinical Relevance

    Complications and readmission after THA pose a significant burden not just to the patient but also to the U.S. healthcare system. As such, minimizing complications while maximizing cost is of paramount importance.

    Although previous studies have elucidated some important answers regarding readmission following THA, this study attempts to prospectively investigate a much larger and diverse healthcare system, making the results more generalizable to the greater population.

    Infection, hematoma, and wound complications were the most common reasons for readmission. Identifying modifiable and non-modifiable (age, sex, race) risk factors for postoperative complications may help surgeons optimize their patients’ medical condition prior to THA and also set appropriate patient expectations based on individual risk profiles.

    Modifiable risk factors such as BMI should be addressed prior to THA. Comorbidities like pulmonary disease, hypothyroidism, and psychosis may be optimized. LOS should also be closely monitored to reduce the risk of readmission in patients with medical complications.

    Establishing high-volume centers of excellence is also a potential way of reducing these events. The finding of higher-volume surgeons having higher risk of readmission may be attributable to the referral patterns within this healthcare system, as well as the possibility of more complex cases channeled to high-volume surgeons.

    Author Information

    Ryan Roach, MD is an orthopaedic surgery resident at NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York. Ajit Deshmukh, MD is an Assistant Professor of Orthopaedic Surgery, Division of Adult Reconstruction, Department of Orthopaedic Surgery, at NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York.