Pelargonium sidoides extract (EPs® 7630) versus usual care for acute bronchitis in Swiss primary care (PHYTOBRONCH): a pragmatic, open-label, randomised controlled trial

We aimed to assess whether Pelargonium sidoides extract (EPs®7630) reduces symptom duration or antibiotic use compared with usual care in adults with acute bronchitis. We conducted a pragmatic randomised-controlled trial across 36 primary care practices and five walk-in clinics in Switzerland. Adults ( ≥ 18 years) consulting a general practitioner for the first time for a new episode of acute bronchitis, with a cough of up to eight days' duration, were eligible for inclusion. The co-primary outcomes were (1) number of days required to achieve a 50% reduction in symptoms from the peak value, assessed using the Acute Bronchitis Severity Score (ABSS), and (2) the proportion of participants who used antibiotics. Missing data in intention-to-treat (ITT) analyses were multiply imputed. 332 participants were enrolled and randomly assigned: 155 to EPs®7630 and 177 to usual care. Neither co-primary outcomes showed a statistically significant difference between groups. No significant difference in time to 50% reduction of symptoms between the EPs®7630 and usual care groups was observed (adjusted regression coefficient 0.05 [95% CI - 0.13-0.23]; p = 0.578). Antibiotic use was 7 percentage points lower (31% relative reduction) in the EPs®7630 group (17.4%, 20 of 155) than in the usual care group (25.2%, 33 of 177), although the difference was not statistically significant (adjusted risk ratio 0.78 [95% CI 0.49-1.26]; p = 0.309). Adverse events were reported more frequently in the EPs®7630 group (32.3%, 50 of 155) than in the usual care group (21.5%, 38 of 177; hazard ratio 1.40 [95% CI 1.03-1.89]; p = 0.030); all adverse drug events were mild. EPs®7630 did not reduce symptom duration or antibiotic use significantly and was associated with more frequent events, that were all mild and previously described. Despite the absence of statistical significance, the observed reduction in antibiotic use warrants further investigation in larger trials to clarify its potential role within antimicrobial stewardship strategies.