Who Gets Pneumonia after Surgery?

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The summary below is from the full report titled "Development and Validation of a Multifactorial Risk Index for Predicting Postoperative Pneumonia after Major Noncardiac Surgery." It is in the 20 November 2001 issue of Annals of Internal Medicine (volume 135, pages 847–857). The authors are AM Arozullah, SF Khuri, WG Henderson, J Daley, and the participants in the National Veterans Affairs Surgical Quality Improvement Program.

What is the problem and what is known about it so far?

Pneumonia (infection of the lung tissue) is a serious complication that sometimes occurs after major surgery. It causes such symptoms as fever, shortness of breath, cough, and chest pain. It often requires treatment with antibiotics and lengthens the time until the patient is well enough to leave the hospital. Pneumonia after surgery is a very serious problem because 20% to 40% of affected patients die within 30 days of surgery. If physicians knew which patients are most likely to get pneumonia after surgery, they could target efforts to prevent this complication. Pneumonia is more common after certain types of operations, and older and weaker patients are more likely to get pneumonia. As yet, physicians do not have a reliable method of identifying which patients are most likely to get pneumonia after surgery.

Why did the researchers do this particular study?

To develop a tool that helps predict who will get pneumonia after major noncardiac (not heart related) surgery.

Who was studied?

316,071 patients who had major noncardiac surgery at 100 Veterans Affairs medical centers between 1995 and 1999. Most were men 50 to 80 years old.

How was the study done?

Nurses reviewed medical records of patients to identify findings that predict pneumonia, surgery data, and outcomes. They also contacted patients 30 days after surgery. Using data from 160,805 patients, the researchers developed a way to use the most accurate patient factors to identify patients with the greatest risk for postoperative pneumonia. They then tested the accuracy of their method by applying it to the other 155,266 patients.

What did the researchers find?

Fewer than 2% of patients had pneumonia after surgery. Of these, 21% died within 30 days. Patient characteristics associated with higher risk for pneumonia were age older than 60 years, regular use of steroid drugs (like prednisone), chronic lung disease, history of major stroke, recent alcohol and tobacco use, recent weight loss, requiring more than 4 units of transfused blood before surgery, and impaired physical or mental function. Several types of surgery increased the risk for pneumonia: emergency surgery; general rather than spinal anesthesia; and surgeries that involved the brain, neck, chest, upper abdomen, or arteries in the abdomen or legs. If a person had few or none of these characteristics, only 2 in 1000 patients developed pneumonia. Fifteen percent of persons with several risk factors developed pneumonia.

What were the limitations of the study?

The researchers used charts to obtain data; information about some potential risk factors was limited or missing from the charts. Almost all of the patients were men; whether different factors would predict postoperative pneumonia in women is not clear.

What are the implications of the study?

A tool that uses patient and surgical characteristics can help doctors estimate patients' risk for pneumonia after noncardiac surgery. This information could be helpful in deciding about elective surgery or preventing pneumonia when surgery is unavoidable. However, no one knows whether clinicians can use the tool to help target preoperative testing and recommendations or postoperative care.