Radiology Resource Utilization During an H1N1 Influenza Outbreak

Purpose

This study was conducted to evaluate the radiology resources utilized by patients infected with novel influenza A (H1N1) during the 2009 summer outbreak to aid in pandemic planning for the 2010 influenza season.

Materials and Methods

Of the 222 patients diagnosed or presumed to have H1N1 infection in the authors' health system from May 1 to July 18, 2009, 66 received imaging, including at least one chest imaging study directly related to the infection. Fourteen of these patients required advanced mechanical ventilation and were admitted to the intensive care unit (ICU; group 1); the remainder were managed as outpatients (27 of 52) or required brief hospitalizations (25 of 52) without mechanical ventilation (group 2; n = 52). The imaging histories of all 66 patients were reviewed for the period of hospitalization for group 1 patients and from 10 days before to 30 days after the diagnosis of influenza infection for group 2 patients to determine the number, types, and temporal distribution of radiology procedures performed during the flu outbreak.

Results

Thirty percent of all patients with known or presumed influenza (H1N1) underwent radiologic imaging. The 14 patients in the ICU received a total of 469 chest radiographic studies (mean, 33.5), 15 thoracic CT examinations, and 170 additional imaging studies, the most common of which were 72 abdominal radiographic studies and 16 abdominal CT examinations. Seventy-one percent (334 of 469) of all the radiographic examinations in ICU patients were obtained during a single month. In contrast, group 2 patients received a total of 71 chest radiographic studies (mean, 1.4), 6 thoracic CT examinations, and 28 additional imaging studies, spread roughly evenly over the study period, with a subtle peak in early June.

Conclusions

The majority of patients with H1N1 infection (70%) received no imaging studies. Patients sufficiently ill to require some level of imaging had, on average, just over one chest radiographic study. The 6% of patients who required ICU stays received an average of 33.5 chest radiographic studies and one thoracic CT examination. This information should be useful for health care organizations in planning their radiology resource needs during an H1N1 flu pandemic.

Key Words: Radiology resource utilization, H1N1, influenza