Standardized interpretation of paediatric chest radiographs for the diagnosis of pneumonia in epidemiological studies.
BACKGROUND
Although radiological pneumonia is used as an outcome measure in epidemiological studies, there is considerable variability in the interpretation of chest radiographs. A standardized method for identifying radiological pneumonia would facilitate comparison of the results of vaccine trials and epidemiological studies of pneumonia.


METHODS
A WHO working group developed definitions for radiological pneumonia. Inter-observer variability in categorizing a set of 222 chest radiographic images was measured by comparing the readings made by 20 radiologists and clinicians with a reference reading. Intra-observer variability was measured by comparing the initial readings of a randomly chosen subset of 100 radiographs with repeat readings made 8-30 days later.


RESULTS
Of the 222 images, 208 were considered interpretable. The reference reading categorized 43% of these images as showing alveolar consolidation or pleural effusion (primary end-point pneumonia); the proportion thus categorized by each of the 20 readers ranged from 8% to 61%. Using the reference reading as the gold standard, 14 of the 20 readers had sensitivity and specificity of > 0.70 in identifying primary end-point pneumonia; 13 out of 20 readers had a kappa index of > 0.6 compared with the reference reading. For the 92 radiographs deemed to be interpretable among the 100 images used for intra-observer variability, 19 out of 20 readers had a kappa index of > 0.6.


CONCLUSIONS
Using standardized definitions and training, it is possible to achieve agreement in identifying radiological pneumonia, thus facilitating the comparison of results of epidemiological studies that use radiological pneumonia as an outcome.
Cherian
Thomas
T
Initiative for Vaccine Research, Department of Immunization, Vaccines and Biologicals, World Health Organization, 1211 Geneva 27, Switzerland. cheriant@who.int
Mulholland
E Kim
EK
Carlin
John B
JB
Ostensen
Harald
H
Amin
Ruhul
R
de Campo
Margaret
M
Greenberg
David
D
Lagos
Rosanna
R
Lucero
Marilla
M
Madhi
Shabir A
SA
O'Brien
Katherine L
KL
Obaro
Steven
S
Steinhoff
Mark C
MC
D002675:Child, Preschool; D006801:Humans; D015337:Multicenter Studies as Topic; D015588:Observer Variation; D011014:Pneumonia / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology; D013902:Radiography, Thoracic / Q000592:standards*; D012015:Reference Standards; D012680:Sensitivity and Specificity