At admission interleukin (IL)-6 (standardised mean difference: 1.41 (0.04-2.77), <i>p</i> = 0.04), cytokeratin fragment 21-1 (CYFRA21-1; 0.53 (0.19-0.86), <i>p</i> = 0.002) and leucocyte count (0.28 (0.05-0.50), <i>p</i> = 0.01) were higher in patients who developed pneumonia. This evidence concerns the gene IL6 and susceptibility to pneumonia measurement.