Meta-analyses are generally regarded as the highest possible level of clinical evidence
(evidence grade Ia) [1]
[2]. The presented meta-analysis aimed to evaluate all available double-blind, randomised,
placebo- controlled studies (RCTs) investigating the effects of ivy leaf dry extract
mono-preparations in the treatment of cough in acute respiratory tract infections
(ARTIs) in adult patients. Two RCTs for ivy leaves dry extract EA 575 (Prospan cough
liquid) met these inclusion criteria and previously had their low risk of bias attested
in an independent review [3]
[4]. In addition to the pooled efficacy quantification from the RCTs, the distribution
of individual results from all 390 randomised patients was examined. This enabled
further analyses, including the quantification of complete cough remission under EA
575 or placebo at treatment end.
The results from all tested parameters favoured EA 575 over placebo, confirming the
significantly stronger improvement of key parameters such as the bronchitis severity
score (BSS). The decrease of the BSS total score in patients treated with EA 575
was approximately one visit (3 days) ahead of that of patients who received placebo
throughout the entire study period. At the follow-up visit, 12% of patients receiving
treatment with EA 575 still showed continuous coughing, while 56% were completely
cough-free. This was in contrast to the placebo group, where 41% of patients still
showed distressing coughing ([Fig. 1]).
Fig. 1 Cough frequency VRS at the end of follow-up. The EA 575 group included more than
twice as many cough-free patients (56%) compared to the Placebo group (26%). Only
12% of patients receiving treatment with EA 575 still showed continuous coughing
at the end of follow-up, compared to 41% of patients receiving placebo.
This meta-analysis increases the level of evidence for EA 575 in the treatment of
cough in adults and represents a major step towards highest evidence based phytomedicine.
