Assessment of radiological progression of simple pneumoconiosis in individual miners.

185-195. The studies reported aimed to determine the best method of assessing radiological progression of simple pneumoconiosis in the individual, so that his progression score could be related to other known information about him. The main concern was with subjects for whom three serial posteroanterior chest radiographs were available at approximately quinquennial intervals. As in other investigations, the 12-point scale of the National Coal Board elaboration led to markedly lower observer error and variability than did the 4-point International Labour Office classification, without distorting levels of progression. Side-by-side reading led to substantially lower observer error and variability than did independent reading. Although the levels of progression in side-by-side reading were on average a little lower than in independent reading, the effect varied between readers and sessions, being frequently reversed. Of the three possible methods of side-by-side assessment, the only one without contraindictions was that in which all three films for each subject were viewed together, and there were some specific indications for this approach. Viewing only the first and last films led to some loss of information; viewing all three possible pairs was very expensive of time, both in organization and in actual reading, and was not entirely consistent (additive); and disguise of temporal order of the films proved impractical. It is concluded that the method of choice for assessing progression in the individual from serial films at roughly quinquennial intervals is to view all films together in known temporal order, recording into the most detailed classification available.