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Low-income patients at increased risk of catastrophic amputation after knee joint replacement
2019/7/1 16:00:09

Above-knee amputation (AKA) is a rare butsevere complication of deep infection after knee replacement surgery.Low-income patients are at increased risk of this catastrophic complication,reports a study in Clinical Orthopaedics and Related Research® (CORR®), a publicationof The Association of Bone and Joint Surgeons®. The journalis published in the Lippincott portfolio by Wolters Kluwer.

Race and sex do not affect the risk of AKAafter periprosthetic joint infection (PJI), according to the new research, ledby Shyam Brahmabhatt, MD, of Rothman Orthopaedic Institute, Philadelphia. In anaccompanying 'Take 5' interview, Dr. Brahmabhatt and CORR Senior Editor M.Daniel Wongworawat, MD, discuss the new evidence on how social factors mayinfluence health outcomes and access to care for patients with complicationsafter knee joint replacement surgery.

Income and Insurance Status Affect AmputationRisk in Patients with Infected Knee Prostheses

Using data from a nationally representativehospital database (Nationwide Inpatient Sample), the researchers identifiedapproximately 33,000 patients diagnosed with PJI after knee joint replacementsurgery between 2010 and 2014. Referring to infection developing around theartificial joint implant (prosthesis), PJI itself is a serious complication,usually requiring further surgery.

In a small number of cases, treatment of theinfection is unsuccessful, requiring amputation of the limb at a level abovethe knee. Of the 33,000 patients with PJI, about three percent had AKA. Theresearchers analyzed risk factors associated with AKA, focusing onsocioeconomic measures (income and insurance status), race, and sex.

Socioeconomic factors were significantlyrelated to AKA risk, even after adjustment for the patients' health status andother characteristics. Patients living in areas (based on ZIP code) in thelowest one-fourth of income were 58 percent more likely to sustain an AKA,compared to those living in the highest-income areas.

Patients on public insurance were also athigher risk. Compared to those with private insurance, the odds of AKA were 94percent higher for Medicare patients and 86 percent higher for Medicaidpatients.

The risk of AKA was not significantlydifferent for black compared to white patients. That's an important finding, asprevious studies had suggested that black race might be a risk factor for AKAafter knee replacement surgery. Risk was also similar for men compared towomen.

Because of the large number of patients whoundergo knee joint replacement and the poor functional outcomes associated withAKA, it is essential to understand the risk factors for this devastatingcomplication. A recent study in CORR® reportedthat the occurrence of AKA due to PJI more than doubled over a 15-year period.

The researchers were surprised to find thatwhere the patient lived had such a major impact on AKA risk. "While ZIPcode may not be a perfect measure of socioeconomic status, it is associatedwith the level of resources that may be available to people living in thatarea," says Dr. Brahmabhatt in his 'Take 5' interview. The researcherscall for further studies to explore strategies to prevent PJI - particularly inpatients from low-income areas.

Drs. Brahmabhatt and Wongworawat discuss thefindings in the context of multidisciplinary efforts to reduce healthdisparities and inequalities in care. "The message that I would impart isthat upholding the principles of equity, social justice, and ensuring communityhealth are important for all physicians," says Dr. Brahmabhatt. "It'simportant to remember that all specialties work together as a team to fulfillvital roles in helping our patients towards that goal."