Conference Coverage

Complications cluster in inflammatory arthritis patients after total knee replacement



– Patients with an inflammatory arthritis had significantly higher rates of infections, transfusions, and readmissions following total knee replacement than did patients without inflammatory arthritis in a study of more than 137,000 Americans who underwent this surgery.

Dr. Susan M. Goodman, Hospital for Special Surgery, New York

Dr. Susan M. Goodman

A sampling of U.S. patients who underwent total knee arthroplasty (TKA) during 2007-2016 showed that among the small percentage of these patients who had an inflammatory arthritis (IA), the rate of periprosthetic joint or wound infection while hospitalized or out to 30 days after surgery was a statistically significant 64% higher relative to patients without inflammatory arthritis, after adjustment for several demographic and clinical confounders, including recent glucocorticoid treatment, Susan M. Goodman, MD, said at the annual meeting of the American College of Rheumatology. The analysis also showed a statistically significant 46% higher relative rate of hospital readmission for any cause during the 90 days after surgery, and a significant 39% relative increase in blood transfusions during the 30 days after TKA in the IA patients.

“These results have important implications for evolving bundled payment models” for TKA, said Dr. Goodman, a rheumatologist at the Hospital for Special Surgery in New York. “Hospitals should receive commensurate resources to maintain access to total TKA for patients with IA.”

For this analysis, Dr. Goodman and her associates classified IA as a patient with a recorded diagnosis of rheumatoid arthritis, spondyloarthritis, or systemic lupus erythematosus if the patient had also received treatment during the year before surgery with a disease-modifying antirheumatic drug, a biologic agent, or a drug that treats systemic lupus erythematosus.

Complications following TKA became a particular concern to hospitals starting in 2013 when the Centers for Medicare & Medicaid Services began a program that penalized hospitals for outcomes such as excessive readmissions following selected types of hospitalizations and also with recent steps to bundle TKA reimbursement with related 90-day outcomes.

“My concern is to ensure that patients with IA aren’t penalized and can maintain access” to TKA despite recent policy moves by the CMS. Faced with potential disincentives to treat patients with an IA, “hospitals might cherry pick patients,” Dr. Goodman said in an interview. The new findings “are a reason for administrators to argue for patients with IA to come out of the cost bundle.”

Dr. Goodman expressed hope that future policies will better reflect the higher levels of risk faced by patients with an IA undergoing TKA. CMS “is pretty responsive,” she said.

The study used data collected by Humana for about 25 million American health insurance beneficiaries during 2007-2016, which included 137,550 people who underwent a TKA. Of these, 3,067 (2%) met the study’s definition for IA, and 134,483 did not. Most of those who did not meet the definition likely had osteoarthritis, Dr. Goodman said. This low percentage of U.S. TKA patients with IA was consistent with numbers in prior reports.

The researchers calculated the relative risk of the IA patients, compared with all the others, for nine potential complications, including acute MI, pneumonia, sepsis, pulmonary embolism, and death. The complications with significantly higher rates among the IA patients after confounder adjustment were 30-day infections, 30-day transfusions, and 90-day readmissions.

Dr. Goodman had no relevant disclosures.

SOURCE: Richardson S et al. Arthritis Rheumatol. 2018;70(Suppl 10): Abstract 1932.

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