Table 1.
Quality assessment of trials of zinc for the treatment of diarrhea
| Quality assessment |
Summary of findings |
|||||||
|---|---|---|---|---|---|---|---|---|
| Directness |
Number of events |
|||||||
| Number of studies (ref.) | Design | Limitations | Consistency | Generalizability to population of interest | Generalizability to intervention of interest | Intervention | Control | RR (95% CI) |
| Mortality (diarrhoea deaths): moderate/low outcome-specific quality | ||||||||
| 15 | cRCT | None | Not statistically significant (−0.5) | Only 1 study (−0.5) | Cannot separate zinc and ORS (−0.5) | 3 | 9 | 66% (−37, 96%)a |
| Mortality (all cause): low outcome-specific quality | ||||||||
| 44,5,15,16 | RCT | None | Consistent and all 4 studies showing benefit | Mostly Asia (−0.5) | Cannot separate zinc and ORS (−0.5) | 21 | 49 | 46% (12, 68%)b |
| Diarrhea hospitalizations: Moderate outcome-specific quality | ||||||||
| 25,6 | cRCT | None | Consistent and both studies showing benefit | All Asia (−0.5) | Cannot separate zinc and ORS (−0.5) | 583 | 784 | 23% (15, 31%)b |
| Diarrhoea duration (>7 days): moderate/low outcome specific quality | ||||||||
| 723–29 | RCT | 4 of 7 included dose < WHO recommendation (−0.5) | Heterogeneity from meta-analysis; 5 of 7 studies show benefit (−0.5) | 2 studies had specialized populations (−0.5) | 346 | 422 | 25% (−9, 49%)c | |
| Diarrhoea prevalence (1–2 weeks): moderate outcome specific quality | ||||||||
| 35,6,15 | cRCT/RCT | None | Heterogeneity from meta-analysis; 2 of 3 studies show benefit (−0.5) | Mostly Asia (−0.5) | 5261 | 6899 | 19% (−4, 47%)c | |
| Mortality (pneumonia deaths): moderate outcome specific quality | ||||||||
| 15 | cRCT | None | Not statistically significant (−0.5) | Only 1 study (−0.5) | 7 | 10 | 28% (−109, 77%)a | |
| Pneumonia hospitalizations: moderate/low outcome specific quality | ||||||||
| 25,6 | cRCT | None | Heterogeneity from meta-analysis; Both studies show benefit; not statistically significant (−1.0) | Mostly Asia (−0.5) | 428 | 830 | 50% (−39, 82%)c | |
| ALRI prevalence: moderate/low outcome specific quality | ||||||||
| 35,6,15 | cRCT/RCT | None | Heterogeneity from meta-analysis; 2 of 3 studies show benefit; not statistically significant (-1.0) | Mostly Asia (−0.5) | 1786 | 2155 | 23% (−25, 53%)c | |
RCT, randomized controlled trial; RR, relative risk.
aDirectly calculated from study results.
bMH pooled RR.
cD & L pooled RR random effect meta-analysis.