1. Subgroup and sensitivity analyses.
| Outcome or subgroup | Studies | Heterogeneity | Statistical Method | Effect estimate |
Test for subgroup differences (P value) |
| All‐cause mortality, outcomes < 1 year since randomisation | 13 | Chi2 = 34.29, df = 12; P < 0.001; I2 = 65% | Risk ratio (GIV, fixed, 95% CI) | 0.83 (0.75 to 0.92) | NA |
| All‐cause mortality, outcomes 13 months to 59 months since randomisation | 6 | Chi2 = 15.75, df = 5; P < 0.001; I2 = 68% | Risk ratio (GIV, fixed, 95% CI) | 0.88 (0.81 to 0.97) | NA |
| All‐cause mortality at longest follow‐up (subgroup analysis): Asia | 12 | Chi2 = 42.65, df = 10; P < 0.001; I2 = 77% | Risk ratio (GIV, fixed, 95% CI) | 0.90 (0.84 to 0.96) | 0.83 |
| All‐cause mortality at longest follow‐up (subgroup analysis): Africa | 6 | Chi2 = 10.06, df = 5; P = 0.07; I2 = 50% | Risk ratio (GIV, fixed, 95% CI) | 0.86 (0.75 to 0.98) | |
| All‐cause mortality at longest follow‐up (subgroup analysis): Latin America | 1 | NA | Risk ratio (GIV, fixed, 95% CI) | 1.00 (0.14 to 7.08) | |
| All‐cause mortality at longest follow‐up, by national child mortality rate (subgroup analysis): high (> 40/1000) | 17 | Chi2 = 53.07, df = 16 (P < 0.001; I2 = 70% | Risk ratio (GIV, fixed, 95% CI) | 0.89 (0.84 to 0.94) | 0.9 |
| All‐cause mortality at longest follow‐up, by national child mortality rate (subgroup analysis): low (< 40/1000) | 2 | NA | Risk ratio (GIV, fixed, 95% CI) | 1.00 (0.14 to 7.08) | |
| All‐cause mortality at longest follow‐up (sensitivity analysis): random‐effects model | 19 | Tau2 = 0.04; Chi2 = 44.00, df = 17; P = 0.001; I2 = 61% | Risk ratio (GIV, fixed, 95% CI) | 0.76 (0.66 to 0.88) | NA |
| All‐cause mortality at longest follow‐up (sensitivity analysis): without DEVTA trial | 18 | Chi2 = 30.38, df = 16; P = 0.02; I2 = 47% | Risk ratio (GIV, fixed, 95% CI) | 0.77 (0.70 to 0.84) | NA |
| All‐cause mortality at longest follow‐up (sensitivity analysis): ICC = 0.002 (assumes no impact of clustering for studies with unknown ICC) | 19 | Chi2 = 57.02, df = 16; P < 0.001; I2 = 72% | Risk ratio (GIV, fixed, 95% CI) | 0.89 (0.84, 0.94) | NA |
| All‐cause mortality at longest follow‐up (sensitivity analysis): ICC = 0.010 (assumes high impact of clustering for studies with unknown ICC) | 19 | Chi2 = 47.87, df = 16; P < 0.001; I2 = 67% |
Risk ratio (GIV, fixed, 95% CI) | 0.89 (0.84 to 0.94) | NA |
| Mortality due to diarrhoea, outcomes < 1 year since randomisation | 6 | Chi2 = 5.23, df = 5; P = 0.39; I2 = 4% | Risk ratio (GIV, fixed, 95% CI) | 0.76 (0.61 to 0.95) | NA |
| Mortality due to measles, outcomes < 1 year since randomisation | 4 | Chi2 = 0.52, df = 3; P = 0.91; I2 = 0% | Risk ratio (GIV, fixed, 95% CI) | 0.85 (0.52 to 1.37) | NA |
| Mortality due to meningitis, outcomes < 1 year since randomisation | 1 | NA | Risk ratio (GIV, fixed, 95% CI) | 5.79 (0.22 to 153.24) | NA |
| Mortality due to LRTI, outcomes < 1 year since randomisation | 6 | Chi2 = 5.66, df = 5; P = 0.34; I2 = 12% | Risk ratio (GIV, fixed, 95% CI) | 0.66 (0.40 to 1.10) | NA |
| Diarrhoea incidence at longest follow‐up (sensitivity analysis): analysis without studies Cheng 1993; Chowdhury 2002 | 13 | Heterogeneity: chi2 = 30.71, df = 12; P = 0.002; I2 = 61% | Risk ratio (GIV, fixed, 95% CI) | 0.96 (0.93 to 1.00) | NA |
| Diarrhoea incidence, outcomes < 1 year since randomisation | 13 | Chi2 = 51.64, df = 11; P < 0.001; I2 = 79% | Risk ratio (GIV, fixed, 95% CI) | 0.93 (0.89 to 0.96) | NA |
| Diarrhoea incidence at longest follow‐up (sensitivity analysis): random‐effects model | 15 | Tau2 = 0.07; Chi2 = 219.04, df = 14; P < 0.001; I2 = 94% | Risk ratio (GIV, random, 95% CI) | 0.84 (0.73, 0.98) | NA |
| Measles incidence, outcomes < 1 year since randomisation | 5 | Chi2 = 0.24, df = 4; P = 0.99; I2 = 0% | Risk ratio (GIV, fixed, 95% CI) | 0.54 (0.36 to 0.80) | NA |
| Malaria incidence, outcomes 1 + years since randomisation (subgroup analysis): age | 1 | NA | Risk ratio (M‐H, fixed, 95% CI) | 0.73 (0.60 to 0.88) | NA |
| LRTI Incidence, outcomes < 1 year since randomisation | 11 | Chi2 = 5.23, df = 8; P = 0.73; I2 = 0% | Risk ratio (GIV, fixed, 95% CI) | 0.96 (0.89 to 1.04) | NA |
| Bitot's spots incidence, outcomes < 1 year since randomisation | 1 | NA | Risk ratio (GIV, fixed, 95% CI) | 0.93 (0.76 to 1.14) | NA |
| Bitot's spots prevalence, outcomes < 1 year since randomisation | 3 | Chi2 = 6.06, df = 2; P = 0.05; I2 = 67% | Risk ratio (GIV, fixed, 95% CI) | 0.43 (0.33 to 0.56) | NA |
| Night blindness prevalence, outcomes < 1 year since randomisation | 1 | NA | Risk ratio (GIV, fixed, 95% CI) | 0.30 (0.17 to 0.52) | NA |
| Xerophthalmia incidence, outcomes < 1 year since randomisation | 2 | NA | Risk ratio (GIV, fixed, 95% CI) | 0.88 (0.72 to 1.07) | NA |
| Vitamin A serum retinol level, outcomes < 1 year since randomisation | 11 | Chi2 = 178.42, df = 10; P < 0.001; I2 = 94% | Standardised mean difference (GIV, fixed, 95% CI) | 0.45 (0.37 to 0.53) | NA |
| Vitamin A serum retinol level at longest follow‐up (sensitivity analysis): random‐effects model | 14 | Tau2 = 0.13; Chi2 = 278.45, df = 14; P < 0.001; I2 = 95% | Standardised mean difference (GIV, random, 95% CI) | 0.50 (0.30 to 0.70) | NA |
CI: confidence interval; GIV: Generic inverse variance; LRTI: lower respiratory tract infection;M‐H: mantel Haenszel method;NA: not applicable.