Table 1.
Search strategies in PubMed.
| Search | Search terms of query |
| #1 | Chronic bronchitis [MeSH Terms] |
| #2 | Chronic bronchitis [Title/Abstract] |
| #3 | CB [Title/Abstract] |
| #4 | Chronic obstructive pulmonary disease [MeSH Terms] |
| #5 | Chronic obstructive pulmonary disease [Title/Abstract] |
| #6 | Lung disease [MeSH Terms] |
| #7 | Lung disease [Title/Abstract] |
| #8 | Pulmonary Disease [MeSH Terms] |
| #9 | Pulmonary Disease [Title/Abstract] |
| #10 | Bronchitis, Chronic [MeSH Terms] |
| #11 | (COPD OR COAD OR COBD) [Title/Abstract] |
| #12 | #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11 |
| #13 | (Probiotics OR probiotic OR prebiotics OR prebiotic OR synbiotics OR synbiotic OR exp Lactobacillus OR Lactobacillus OR lactobacilli OR exp Bifidobacterium OR exp Bacillus OR bacilli OR bacillu OR Clostridium butyricum OR clostridium butyricum OR streptococcus thermophill OR exp Escherichia coli OR propionibacteria) [Title/Abstract] |
| #14 | Clinical trial [Title/Abstract] |
| #15 | Randomised or randomized [Title/Abstract] |
| #16 | Randomized controlled trial [Title/Abstract] |
| #17 | Placebo [Title/Abstract] |
| #18 | #14 OR #15 OR #16 OR #17 |
| #19 | #12 AND #13 AND #18 |