Table 3.
Pooling the Results of the High Dose Zinc Acetate Trials
| Trial | Intervention | Effect of Zinc Acetate on Common Cold Durationa (95% CI) | |||||
|---|---|---|---|---|---|---|---|
| Zinc | Placebo | ||||||
| No. of Colds | Mean Duration of Colds (Days) | SD | No. of Colds | Mean Duration of Colds (Days) | SD | ||
| Petrus et al. 1998 [22]b | 52 | 3.80 | 1.63 | 49 | 5.10 | 2.96 | -26% (-44%, -7%) |
| Prasad et al. 2000 [25] | 25 | 4.5 | 1.6 | 23 | 8.1 | 1.8 | -44% (-56%, -33%) |
| Prasad et al. 2008 [21] | 25 | 4.00 | 1.04 | 25 | 7.12 | 1.26 | -44% (-53%, -35%) |
| Pooled results | 102 | 97 | -42% (-48%, -35%) | ||||
a
There is no evidence of heterogeneity over these three trials: χ2(2 df) = 3.5 (P = 0.2), I2 = 43%. Calculations were done by using the RevMan program [35].
b
Petrus et al. [22] reported the results inaccurately to only one decimal place, giving 3.8 and 5.1 for the mean duration of colds and 0.2 and 0.4 for the SE of the mean in the zinc and placebo groups, respectively. These more accurate figures were kindly provided by Ken Lawson (March 4, 2009).