ABCDEFGHIJKLMNOPQRSTUVWXYZAA
1
We began with all 13 trials of water quality interventions reporting under-5 all-cause mortality included in the Kremer et al. meta-analysis. We excluded trials in which the intervention did not involve chlorination. We excluded trials with follow-up of less than one year, which excludes shorter trials that tend to be less robust and may have greater publication bias. This also limits excess uncertainty that is intruduced by pooling trials with large variation in follow-up length. We excluded Haushofer et al. for two reasons. First, it is a follow-up of the Null 2018 RCT, so it does not meet the independence assumption underlying this meta-analysis method. Second, we find the effect size implausibly large (including the bottom of the 95% confidence interval) given the modest intervention effect on chlorination rates (see our accompanying water quality report for more information). We then generated weights based on inverse variance (a common meta-analysis method that minimizes variance of the mean), and similarity to simple chlorination interventions such as Dispensers for Safe Water and in-line chlorination, and took the weighted mean of the effect size of each trial on mortality. The pooling method was designed with help from statistics consultant Megan Higgs. Unpublished mortality data for Reller 2003 and Boisson 2013 are included with permission from the authors.
2
3
TrialIntervention type
Addl interventions?
TypeControl n
Control deaths
Control nondeaths
Treatment n
Treatment deaths
Treatment nondeaths
Mortality RR
ln(Mortality RR)
SE of ln(RR)
1/variance weight
Similarity weight
Total weight% weight
4
Reller 2003Chlorinationyes
Safe storage vessel
187218573937360.38-0.970.911.20.881.12%
5
Boisson 2013Chlorinationno1484114831507215051.970.681.220.71.000.71%
6
Luby 2018Chlorinationyes
Safe storage vessel
1306621244656276290.87-0.140.2319.70.7514.729%
7
Null 2018Chlorinationno1895731822888308580.88-0.130.2122.01.0022.043%
8
Humphrey 2019Chlorinationyes
Handwashing, infant play space and education to prevent geophagia, education on hygienic prep of complementary food, education on safe disposal of feces
95950909995499460.94-0.060.2026.10.5013.025%
9
10
Pooled ln(RR)-0.12
11
Pooled relative risk0.88
12
SE of ln(RR)0.12
13
95% CI lower bound0.69
14
95% CI upper bound1.13
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100