Bias and `Overcall' in Interpreting Chest Radiographs in Young Febrile Children

Abstract

Few studies have examined the diagnostic validity of the examination physician's interpretation of chest radiographs in young febrile children, and none (to our knowledge) the extent to which the "official" (ie, the radiologist's) reading may be biased by access to the examining physician's reading and to other clinical information. The authors studied 287 consecutive chest radiographs obtained in 286 febrile children 3 to 24 months of age without chronic cardiopulmonary disease or known asthma who presented to a children's hospital emergency department between March 1989 and August 1990. The readings by treating pediatricians, official pediatric radiologists, and a "blind" pediatric radiologist were compared. Official radiologists had access to the treating pediatricians' readings and the clinical information provided on the radiography requisition. The blind radiologist knew only that each child was 3 to 24 months of age and febrile, and he was asked to judge the presence or absence of pneumonia. Using the blind radiologist's reading as the "gold standard" for judging validity of the treating physicians' and official radiologists' readings, sensitivity (.677 vs .647), specificity (.828 vs .849), positive predictive value (PPV, .537 vs .571), and kappa index (kappa, .462 vs .475) were quite similar. By contrast, agreement by the treating physicians was considerably higher with the official radiologists' readings as gold standard: sensitivity = .756, specificity = .922, PPV = .795, and kappa = .688. When the treating physician's reading was positive, the official radiologists' positivity rate was much higher than the blind radiologist's (74.4% vs 51.8%, P less than .005), sensitivity was high (.884) but specificity was low (.436), PPV was .663, and kappa was .326.(ABSTRACT TRUNCATED AT 250 WORDS)