Usefulness of chest radiographs in children with acute lower respiratory tract disease.

To determine how frequently and under what circumstances the chest radiograph changes pre-x-ray diagnoses and plans for management of suspected acute lower respiratory tract disease, experienced pediatricians performed a three-phased sequential evaluation (observation, history, physical examination), determined an initial diagnosis and the need for a chest radiograph after each phase, and recorded pre- and post-x-ray diagnoses and plans of management. Of the 102 children evaluated, the chest radiograph resulted in a change of the pre-x-ray diagnosis in 21% and pre-x-ray management plans in 16%. In the majority of these cases, a diagnosis previously considered less likely was "ruled in" or therapy was instituted rather than withheld. More important, when the pattern of decision making was consistent, with the initial diagnosis and the need for a chest radiograph remaining the same throughout all phases, the chest radiograph resulted in a change of pre-x-ray diagnosis in five (10%) of 48 patients, compared with a change in 16 (30%) of 54 when the pattern was inconsistent (P less than 0.02). Similarly, when the pattern was consistent, the pre-x-ray management was modified in only three (6%) of 48 patients versus 13 (24%) of 54 inconsistent cases (P less than 0.015). Chest radiographs are least useful when information from sequential observation, history, and physical examination is consistent in suggesting the same diagnosis and need for a chest radiograph. Radiographs appear to have greater impact on diagnosis and management when any inconsistencies arise.