The quality of evidence is downgraded by study limitations (unclear blinding) and by inconsistency (statistical heterogeneity).
A Cochrane review [Abstract] 1 included 8 studies with a total of 1 771 subjects. Three studies of efficacy in acute bronchitis in adults showed effectiveness for most outcomes in the liquid preparation but not for tablets (table T1).
| Outcome | Relative effect (95% CI) | Assumed risk - Placebo | Corresponding risk - P. sidoides (95% CI) | Participants (studies) |
|---|---|---|---|---|
| Failure to recover by day 7 (complete resolution of all symptoms) - liquid preparation | RR 0.66 (0.52 to 0.83) | 953 per 1000 | 629 per 1000(495 to 791) | 341(2 studies) |
| Failure to recover by day 7 (complete resolution of all symptoms) - tablet preparation | RR 0.95 (0.91 to 0.99) | 990 per 1000 | 941 per 1000(901 to 980) | 405(1 study) |
Three other studies showed similar results for acute bronchitis in children (Table T2). For both meta-analyses, subtotals were not pooled due to relevant heterogeneity induced by type of preparation. One study each was available for the treatment of acute sinusitis and the common cold in adults. The study in sinusitis (n=103) showed significant treatment effects (RR 0.43, 95% CI 0.3 to 0.62), and the study in the common cold (n=103) demonstrated efficacy after 10 days (RR 0.41, 95% CI 0.29 to 0.60), but not 5 days (RR 0.96, 95% CI 0.9 to 1.03). There were no valid data for the treatment of other acute respiratory tract infections. Adverse events were more common with P. sidoides, but none were serious.
| Outcome | Relative effect (95% CI) | Assumed risk - Placebo | Corresponding risk - P. sidoides (95% CI) | Participants (studies) |
|---|---|---|---|---|
| Failure to recover by day 7 (complete resolution of all symptoms) - liquid preparation | RR 0.82 (0.77 to 0.88) | 971 per 1000 | 796 per 1000(748 to 854) | 420(2 studies) |
| Failure to recover by day 7 (complete resolution of all symptoms) - tablet preparation | RR 0.96 (0.89 to 1.03) | 911 per 1000 | 874 per 1000(811 to 938) | 399(1 study) |
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