Interobserver concordance
The results of the Fleiss kappa assessed for alveolar pattern yielded a value of 0.421 for the first group and 0.49 for the second group, which represents a moderate agreement.  The highest Cohen kappa values were 0.524 within group 1 and 0.44 within group 2, both corresponding to alveolar opacities. For more information about Fleiss Kappa and Cohen Kappa values please see supplementary appendix 2.