REPRODUCIBILITY OF THE HISTOLOGIC DIAGNOSIS OF PNEUMONIA AMONG A PANEL OF 4 PATHOLOGISTS - ANALYSIS OF A GOLD STANDARD

Study objective: To establish a histologic diagnosis of pneumonia by c onsensus of a panel of pathologists, to test the interobserver and int raobserver variation in the histologic diagnosis of pneumonia, to comp are the diagnostic accuracy of diagnosing pneumonia with and without p reselected histologic criteria, and to establish more specific histolo gic criteria for the diagnosis of pneumonia. Methods: The study group consisted of 39 patients who died after a mean of 14 days of mechanica l ventilation. A postmortem open lung biopsy was performed on all pati ents. The tissue was reviewed independently by four pathologists who c ategorized the slides from each patient as showing or not showing pneu monia. Interobserver variation was calculated using the kappa statisti c. Sis months following the initial evaluation, the same slides were r esubmitted to one of the. pathologists for reevaluation to look for in traobserver error. Finally, the slides were reviewed and categorized b y the criteria of Johanson et al into no pneumonia, mild, moderate, or severe bronchopneumonia. A comparison was made of the patients select ed as demonstrating histologic pneumonia by each of the examinations. Results: The reliability coefficient (kappa) measuring agreement among the four pathologists was good at 0.916. However, the prevalence of p neumonia as determined by each of the four pathologists varied; pathol ogist A, 15 of 39 (38%); pathologist B, 12 of 39 (31%); pathologist C, 9 of 39 (23%); and pathologist D, 7 of 39 (18%). Resubmitting the sam e slides to the same pathologist 6 months later resulted in reclassifi cation of 2 of 39 patients. Using the histologic criteria of Johanson and colleagues, 14 patients were selected as having pneumonia compared with only nine patients selected by consensus of three of four pathol ogists. Conclusions: Recognition of histologic pneumonia varies among pathologists. The preselected criteria of Johanson and colleagues dete cted histologic pneumonia in eight of nine patients picked by consensu s of pathologists, but six additional patients classified as ''no hist ologic pneumonia'' by the consensus of pathologists were judged to hav e histologic pneumonia by these criteria. The results established the necessity for standardization of histologic criteria for studies using biopsy as the gold standard for bacterial pneumonia. An atlas showing the criteria used in our selection was developed.