Table 2– Demographics of patients included in the sputum analysis
CharacteristicAll patientsPPM positivePPM negativep-value#
Subjects n408918982191
Male sex %<0.001
Age yrs56±15.355.3±15.557.2±15.0<0.001
Exacerbations in previous year2.5±1.92.4±1.62.5±2.10.614
Median (IQR) duration of exacerbation before study entry days2 (5)2 (5)2 (6)0.130
Past or present smoker3280 (80.2)1629 (85.8)1651 (75.4)<0.001
Use of long-term bronchodilators or steroids261 (6.4)116 (6.1)147 (6.7)0.135
Median (IQR) CRP level mg·L−10.70 (1.79)0.69 (2.17)0.71 (1.56)0.551
Fever present744 (18.2)294 (15.5)389 (20.5)0.005
  • Data are presented as mean±sd or n (%), unless otherwise stated. PPM: potentially pathogenic microorganism; IQR: interquartile range; CRP: C-reactive protein. #: PPM positive versus PPM negative; : data were not collected for all patients in the study for these characteristics. Cochrane–Mantel–Haenszel test, adjusting for study, categorical variables, and using an ANOVA, also adjusting for study, for the continuous variables.