Falling pneumonia rates deceiving

Although news of falling pneumonia rates seems promising, new research indicates the lower rates might only be a trick of the eye. Changes in diagnostic coding, rather than clinical improvements, may explain the decline, according to a study published in today's Journal of American Medical Association (JAMA).

Researchers looked at data from 2003 to 2009 for patients with pneumonia alone, with sepsis plus pneumonia and respiratory failure combined with pneumonia, comparing the results of outcomes when providers defined pneumonia differently, that is, a primary diagnosis versus a secondary diagnosis. They found that when providers defined pneumonia as the principal diagnosis, hospitalization dropped 27.4 percent (from 5.5 to 4.0 per 1,000 patients).

But when providers listed the secondary diagnosis as pneumonia, with a principal diagnosis of sepsis, hospitalization rates increased a whopping 177.6 percent (0.4 to 1.1 per 1,000). When they listed the secondary diagnosis as pneumonia, with principal diagnosis of respiratory failure, hospitalization rose 9.3 percent (from 0.44 to 0.48 per 1,000). The annual hospitalization rate dropped 12.5 percent (from 6.3 to 5.6 per 1,000) when the three diagnosis groups were combined to gauge the actual rates to reduce coding changes.

The findings could have serious implications, the authors wrote. "[The data] suggest that attempts to measure the outcomes of patients with pneumonia by studying only those who receive a principal diagnosis of pneumonia will be biased toward increasingly less severe cases. This is especially problematic in the context of longitudinal studies that are subject to the effects of temporal trends in coding practice," they wrote.

As the leading cause of illness and death in U.S. adults, pneumonia accounts for more than 1 million hospital admissions, totaling $10.5 billion in aggregate costs, according to the research announcement. As the Centers for Medicare & Medicaid Services continues to look at hospital performance, particularly around pneumonia rates as one of the key reimbursement measures, the authors noted measurements and comparisons "may also be biased if there is variation across hospitals in their use of the sepsis and respiratory failure codes," they said.

For more information:
- here's the JAMA study abstract
- see the press release

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