"Our study would suggest if you really want to know what's happening with pneumonia, it's not enough to look at coded groups for pneumonia. You have to also look at these other groups with a secondary diagnosis of pneumonia," said Lindenauer.
An accompanying editorial published in the journal suggests coding nuances may also affect the way other diseases, such as heart disease, are evaluated.
Dr. Rohit Bhalla, chief quality officer at Montefiore Medical Center in New York City, who was not involved in the study, concurred that coding is complex and needs further analysis. He said new coding methods will soon be introduced that could complicate matters further.
"You have to understand administrative data's strengths and limitations," Bhalla said. "You have to be careful and circumspect about implying that small changes in data relate to care." He suggested it might be more accurate to use both administrative and clinical information from a patient's chart when studying disease trends, treatments and survival.
For more on pneumonia, see the U.S. National Library of Medicine.
SOURCES: Peter Lindenauer, M.D., M.Sc., director, Center for Quality of Care Research, Baystate Medical Center, Springfield, Mass., and associate professor, medicine, Tufts University School of Medicine, Boston; Rohit Bhalla, M.D., chief quality officer, Montefiore Medical Center, Bronx, N.Y.; April 4, 2012, Journal of the American Medical Association
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