FRIDAY, Oct. 22 (HealthDay News) -- Misdiagnosis of pneumonia is common among patients readmitted to the hospital shortly after a hospitalization for the same illness, according to two companion studies.

These misdiagnoses result in the overuse of antibiotics and increased health care costs, said the researchers at the Henry Ford Hospital in Detroit.

They examined the medical records of 127 patients who were diagnosed with pneumonia and readmitted within 30 days of a hospital discharge. Of this group, they found that 92 patients -- or about 72 percent -- were misdiagnosed with pneumonia upon readmission.

Among the other findings:

• Blacks were more than twice as likely as whites to be misdiagnosed with pneumonia.
• Smokers and patients with lung disease were likely to be misdiagnosed.
• About 72 percent of misdiagnoses occurred in the emergency department.
• Less than 33 percent of the patients had any outpatient follow-up care prior to their readmission to hospital.

Possible reasons for the misdiagnoses include abnormalities on chest X-rays and pre-existing lung disease, said the researchers.

The findings were slated to be presented Friday in Vancouver at the annual meeting of the Infectious Diseases Society of America.

"These studies show that we need to increase awareness among physicians about using the diagnostic standards and criteria set forth in the Centers for Disease Control and Prevention's National Healthcare Safety Network for diagnosing pneumonia at the time of readmission," Dr. Hiren Pokharna, an infectious disease fellow and lead author of the studies, said in a hospital news release.

"This also points to the importance of using X-ray for ruling out pneumonia. And once pneumonia is ruled out, the antibiotics can be discontinued," he added.

More information

The American Lung Association has more about pneumonia.