Objectives
To evaluate the accuracy of emergency department (ED) physicians’, the Loeb criteria, and CDC guideline diagnoses of acute bacterial infection in older adults compared to a gold standard expert review.
Design
Prospective, observational study.
Setting
Urban, tertiary-care ED.
Participants
ED patients aged ≥65 years, excluding those incarcerated, traumas, non-English speaking, or unable to consent.
Measurements
Two physician experts identified bacterial infections using clinical judgement, patient surveys, and medical records; a third adjudicated in cases of disagreement. Agreement and test characteristics were measured for ED physician diagnosis, Loeb criteria, and CDC surveillance guidelines.
Results
Gold-standard review identified bacterial infection in 77/424 patients (18%): 18(4.2%) lower respiratory, 19(4.5%) urinary tract (UTI), 22(5.2%) gastrointestinal, and 15(3.5%) skin/soft tissue. ED physicians diagnosed infection in 71 (17%), but there were 33 with under- and 27 with over-diagnosis. Physician agreement with the gold standard was moderate for infection overall and each infection type (kappa [k] 0.48–0.59), but sensitivity was low (<67%), and negative likelihood ratio (LR[−]) >0.30 for all infections. Loeb criteria had poor sensitivity, agreement, and LR(−) for lower respiratory (50%; k=0.55; 0.51) and UTI (26%; k=0.34; 0.74), but 87% sensitivity (k=0.78; LR[−] 0.14) for skin/soft tissue infection. CDC guidelines had moderate agreement, but poor sensitivity and LR(−).
Conclusions
Infections are often under- and over-diagnosed by emergency physicians in older adults. The Loeb criteria are useful only for diagnosing skin/soft tissue infections. CDC guidelines are inadequate in the ED. New criteria are needed to aid ED physicians in accurately diagnosing infection in older adults.