Hoheisel 1997.
| Methods | Approach: treatment trial Design: randomized; placebo‐controlled, double‐blind |
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| Participants | Numbers: 120 randomized and analyzed (60 Echinacea, 60 placebo)
Setting: company physician of a large furniture‐making factory Demographics: 10% female, mean age 36.5 years Main inclusion criteria: patients presenting with first symptoms of an URTI and having a history of recurrent URTI (> 3 episodes in the previous 12 months) (employees of the furniture‐making factory) |
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| Interventions |
Echinacea: pressed juice of Echinacea purpurea herb
Placebo: "identical in color and ethanol concentration"
Dosage and treatment duration: on day 1 every 2 hours 20 drops, then up to maximally 10 days 3 x 20 drops daily Concurrent medication: "Nine patients in the Echinagard group and 4 in the placebo group reported taking concomitant medication, mainly analgesics and anti‐ulcer agents." These patients were at least included in the ITT‐analysis |
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| Outcomes | Primary: number of patients who developed a 'full' common cold and days until improvement Secondary: symptom diary, global assessments |
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| Notes | Funding source: not stated
Conflict of interest: not stated
No diary data presented, subjective patient definition what was considered a 'full' cold (could be a major problem if patients should have been unblinded) No additional information received |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "Patients were randomized to treatment groups (using the programme Random V5.0)..." |
| Allocation concealment (selection bias) | Unclear risk | Not described |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | "Placebo identical in colour and ethanol concentration; identical bottles". Taste not mentioned, no test of blinding, no description of development/testing of liquid placebo |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All 120 patients randomized completed the study and were analyzed |
| Selective reporting (reporting bias) | High risk | "Recorded subjective symptoms daily in diary card" not shown in tables. Subsample record only of those who report "real cold" may introduce bias |