Table 1 Review eligibility criteria

Participants

 Participants diagnosed with acute exacerbation of COPD

Stable COPD

Index test

 Sputum colour macroscopically assessed by professional healthcare worker or patient reported

Reference standard

 Quantitative culture for potentially pathogenic bacteria on an adequate sputum sample (according to the Murray-Washington or Bartlett criteria)

Outcome

 Data required to populate 2 X 2 table: sensitivity and specificity or true positives, false positives, false negatives and true negatives

Study design

 Prospective studies

Case reports

 Retrospective studies

Case series

 Cross-sectional studies

Ecological studies

Diagnostic case control studies with healthy controls