Published 3/1/2011
Jennie McKee

Heart problems lead to readmission after THA

Cardiac complications are most common reasons for early readmission

The current administration has announced plans to save $26 billion in the next 10 years by lowering Medicare reimbursement payments to hospitals that have high patient readmission rates. These financial ramifications—as well as an increased focus on quality of care issues—have spurred efforts to learn more about why some patients must return to the hospital.

According to a study involving total hip arthroplasty (THA) patients presented by James I. Huddleston, III, MD, at the 2010 annual meeting of the American Association of Hip and Knee Surgeons, a seemingly logical cause of readmission—complications such as congestive heart failure, chronic ischemic heart disease, and cardiac dysrhythmias were the most common reasons for readmission.

Based on these study results, “optimized cardiac status prior to discharge may lead to lower rates of readmission in the future and may also decrease healthcare costs associated with THA,” said Dr. Huddleston.

Designing the study
The researchers evaluated the rates and diagnoses associated with postoperative readmission as well as the length of stay (LOS), working under the hypothesis that reduced LOS would lead to an increase in the rate of readmission.

They abstracted data from the Medicare Patient Safety Monitoring System (MPSMS) on 1,802 Medicare beneficiaries (1,134 females and 668 males; mean age: 74 years) who underwent primary THA from 2002 to 2007.

“These patients represent all patients who had total hip replacement in the MPSMS sample,” Dr. Huddleston said. “The MPSMS sample was randomly selected from the Hospital Payment Monitoring Program, which is another random sample taken for the Centers for Medicare & Medicaid Services and represents approximately 1 million hospital discharges per month.”

Investigators used inpatient data to analyze LOS as well as patient comorbidities. They also used claims data to capture 30-day readmission rates and reasons for readmission.

“We used the chi-square test to analyze readmissions and the t-test to evaluate LOS,” he said.

“Perhaps the strongest aspect of the study,” he continued, “is that we adjusted for patient factors, analyzing readmission and LOS independently to assess the odds of a change in the rates of LOS and readmission during the study period.

“We found that the patient population changed over the course of the study—they became younger and more obese, which had ramifications for our statistical analysis,” he added.

Effect of LOS, cardiac complications
According to Dr. Huddleston, 123 of the 1,802 patients were readmitted in the 30 days after discharge. Researchers found a significant decrease in LOS from 2002 to 2007.

“The average LOS overall for the 6-year period was 4.2 days,” he said. “In the first 3 years, it was 4.4 days, and in the second 3 years, it was 3.8 days.”

The researchers did not, however, find a significant difference in the rate of readmission between 2002 and 2004 (7.1 percent) and 2005 and 2007 (6.3 percent); (odds ratio 0.90, 95 percent confidence interval 0.63–1.30, p = 0.58).

Based on these data, Dr. Huddleston concluded that decreasing LOS was not associated with re-admission rates.

Of the top 10 reasons for readmission, just three conditions—congestive heart failure, chronic ischemic heart disease, and cardiac dysrhythmias—accounted for nearly half (48 percent) of all readmissions (Fig 1). Readmissions for infection and dislocation didn’t make the top 10 list.

“We think the fact that cardiac complications were the most common reason for readmission represents an opportunity to improve patient safety and to reduce costs by optimizing cardiac status preoperatively,” he said. “This may potentially be accomplished by lowering the threshold for screening with dobutamine stress echocardiography, and also with routine postoperative follow-up care with a primary care physician.”

Coauthors of “Readmission and Length of Stay after THA in a National Medicare Sample, 2002–2007” included Mr. John Vorhies; Yun Wang, PhD; James H. Herndon, MD; and William J. Maloney, MD.

Disclosure information: Mr. Vorhies, Dr. Wang, and Dr. Herndon—no conflicts. Dr. Huddleston—Biomet, Smith and Nephew, Porosteon, and Zimmer. Dr. Maloney—Wright Medical Technology, Inc.; Zimmer; ISTO Technologies; Moximed; Abbott; Gillead; Johnson & Johnson; Merck; Pfizer; AO; Biomet; DePuy Spine; DePuy, a Johnson & Johnson Company; Nuvasive; Smith and Nephew; Stryker; and Zimmer.

Bottom Line

  • Although length of stay after THA decreased significantly from 2002 to 2007, readmission rates remained the same.
  • The top 3 reasons for re-admission—comprising 48 percent of the total causes for readmission—were cardiac-related.
  • Based on this study, optimizing cardiac status preoperatively and increasing use of dobutamine stress echocardiography to detect cardiac conditions may improve patient safety.

Jennie McKee is a staff writer for AAOS Now. She can be reached at mckee@aaos.org