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Risk Model Helps Predict, Mitigate Pneumonia Risk after CABG Surgery

ANN ARBOR, MI – What if a hospital knew beforehand which open-heart surgery patients were most likely to develop pneumonia as a post-surgery complication?

That is possible with a new risk model designed to guide clinical decision-making and physician-patient conversations about regimens to pursue before the procedure to help avoid pneumonia, according to a report in Annals of Thoracic Surgery.

Pneumonia occurs in 3.3% of patients and often leads to longer hospital stays and lower odds of survival, according to the University of Michigan-led research. For the study, the researchers analyzed data from 16,084 patients who had coronary artery bypass graft (CABG) surgery at 33 Michigan hospitals.


The result is a list of 17 patient characteristics, including age, race, smoking habits, and white blood cell count, among others, found to be associated with developing pneumonia after cardiac surgery.

"This work reflects an evolution of our understanding of postoperative infections," explained senior study author Donald Likosky, PhD. He said in a University of Michigan Health System press release that the model can help hospitals “go a long way to preserve resources and help patients recover from one of the country's most common cardiac procedures."

According to the study, the strongest indicators for development of pneumonia included the following:

  • admission for heart surgery via the emergency room,
  • a history of lung problems,
  • a long hospital stay before surgery, and
  • low ejection fraction.

Smoking is another well-recognized risk factor for postoperative pneumonia, and study authors said that quitting smoking, even just a month before surgery, can help prevent pneumonia development.

If another complication — leukocytosis — is present, researchers suggested that surgery be delayed, however. "Patients presenting with an elevated white blood cell count before their operation may be mounting an immune response against a pathogen or other challenge, and CABG significantly increases their odds of postoperative pneumonia," pointed out co-author Gaetano Paone, MD, MHSA, a cardiac surgeon at the Henry Ford Health System.

“We identified 17 readily obtainable preoperative variables associated with postoperative pneumonia,” study authors concluded. “This model may be used to provide individualized risk estimation and to identify opportunities to reduce a patient’s preoperative risk of pneumonia through prehabilitation.”