Table 3: Placebo-controlled studies:
Secondary outcomes
| Variables | No of trials | Proportion with ≥1 event, intervention group (%) | Proportion with ≥1 event, control group (%) | Odds ratio (95% CI) | I2 % | P for heterogeneity |
|---|---|---|---|---|---|---|
| Efficacy outcomes | ||||||
| Upper respiratory infection* | 28 | 7931/13493 (58.8) | 7823/13034 (60.0) | 0.96 (0.90 to 1.02) | 4.4 | 0.40 |
| Lower respiratory infection* | 14 | 3583/12167 (29.4) | 3601/12027 (29.9) | 0.98 (0.93 to 1.04) | 0.0 | 0.56 |
| Emergency department attendance and/or hospital admission due to ARI | 18 | 117/9887 (1.2) | 125/9769 (1.3) | 0.90 (0.70 to 1.16) | 0.0 | 1.00 |
| Death due to ARI or respiratory failure | 33 | 14/13612 (0.1) | 11/13058 (0.1) | 1.04 (0.61 to 1.78) | 0.0 | 1.00 |
| Use of antibiotics to treat an ARI* | 13 | 2035/7562 (26.9) | 2082/7423 (28.0) | 0.91 (0.82 to 1.02) | 13.4 | 0.31 |
| Absence from work or school due to ARI | 10 | 378/1527 (24.7) | 364/1044 (34.9) | 0.91 (0.69 to 1.20) | 35.3 | 0.13 |
| Safety outcomes | ||||||
| Serious adverse event of any cause* | 35 | 545/13861 (3.9) | 554/13326 (4.2) | 0.97 (0.86 to 1.09) | 0.0 | 1.00 |
| Death due to any cause | 34 | 117/13854 (0.8) | 97/13293 (0.7) | 1.15 (0.90 to 1.49) | 0.0 | 1.00 |
| Hypercalcaemia | 21 | 50/9294 (0.5) | 39/8919 (0.4) | 1.20 (0.81 to 1.79) | 0.0 | 1.00 |
| Renal stones | 20 | 110/11540 (1.0) | 128/11138 (1.1) | 0.85 (0.66 to 1.10) | 0.0 | 1.00 |
*
This analysis includes a subset of participants in the trial by Pham et al, who completed symptom diaries.