How Treatment Window Impacts CAP Diagnosis

Welker JA, Huston M, McCue JD. Antibiotic timing and errors in diagnosing pneumonia. Arch Intern Med. 2008;168(4):351-356.

Metersky ML. Measuring the performance of performance measurement [editorial]. Arch Intern Med. 2008;168(4):347-348.

Changes to performance measurement goals may have unintended negative consequences, as demonstrated by a retrospective study on the timing of administration of antibiotics for community-acquired pneumonia (CAP) in the emergency department (ED). Welker and colleagues examined whether reducing the time to first antibiotic dose (TFAD) resulted in an increased likelihood of CAP misdiagnosis.

The researchers reviewed medical records for adults who received a diagnosis of CAP from an ED physician at a university-affiliated community teaching hospital in Baltimore during either of two periods: November 2003 through April 2004, when the quality-of-care standard for TFAD was within eight hours of admission, and November 2004 through April 2005, when the standard TFAD had been lowered to four hours. There were 255 patients in the former group and 293 in the latter.

Two analyses were conducted to determine the accuracy of the ED physician's diagnosis of CAP in each patient. When compared with predefined diagnostic criteria for CAP, the ED physician's diagnosis was accurate about 46% of the time during the earlier study period and 34% of the time during the later period. When compared with the discharging physician's diagnosis, the admitting diagnosis was considered accurate 75% and 67% of the time in the respective periods. Delays in accurate diagnosis among misdiagnosed patients were more likely to occur during the later study period. Furthermore, the researchers observed similar mean TFADs in both periods: 167.0 minutes in the earlier period and 157.8 minutes in the later period--both "substantially less than the core measure goals."

The results seem to validate the researchers' concern "that the new TFAD was inadvertently creating a time pressure by adding a deadline to the physicians' decision-making process and thereby influencing the quality of their decisions."

In an accompanying editorial, Mark L. Metersky, MD, also expresses "concern that the pressure to provide antibiotics within four hours has resulted in inappropriate antibiotic use in patients who ultimately are not diagnosed as having pneumonia." He adds that the time-sensitive focus on patients with respiratory illnesses also "may result in delayed care to patients with urgent medical conditions that are not the subject of quality improvement efforts." These concerns have resulted in further amendment of the TFAD goal, which is now six hours.