What zinc supplementation does and does not achieve in diarrhea prevention: a systematic review and meta-analysis

BMC Infectious Diseases

Table 2 Results of subgroup analysis for the outcome of diarrheal incidence

Characteristic	N	SRR	95% CI	95% PI	I²(%)	τ²	95% CI for τ²	Pr(OE) %
Age category
Age range < = 12 months	12	0.95	0.88-1.02	0.77-1.18	69.9	0.0099	0.0000 - 0.0345	30.3
Remaining studies	26	0.89	0.83-0.94	0.71-1.12	61.9	0.0114	0.0029 - 0.0284	13.8
Type of comparison*
Zinc versus placebo	25	0.88	0.82-0.95	0.67-1.16	72.2	0.0173	0.0069 - 0.0404	16.6
Zinc+x versus x	5	0.90	0.85-0.96	0.84-0.96	6.7	0.0003	0.0000 - 0.0256	<0.001
Zinc+x+y versus y	8	0.98	0.82-1.04	0.80-1.20	21.2	0.0014	0.0000 - 0.0269	29.5
Continent of origin
Africa	8	0.92	0.79-1.08	0.67-1.26	43.7	0.0185	0.0000 - 0.1702	27.0
Asia	19	0.91	0.86-0.96	0.74-1.12	72.2	0.0099	0.0038 - 0.0252	17.2
Americas	10	0.90	0.80-1.01	0.66-1.22	68.7	0.0192	0.0059 - 0.0756	22.4
Oceania	1	0.99	0.32-3.06	---	---	---	---	---
Country economy
Low income	14	0.94	0.87-1.01	0.76-1.16	63.4	0.0089	0.0006 - 0.0393	25.6
Lower middle income	12	0.85	0.78-0.94	0.65-1.11	75.5	0.0154	0.0051 - 0.0540	9.5
Upper middle income	11	0.94	0.87-1.02	0.78-1.13	43.0	0.0068	0.0000 - 0.0294	22.7
High income	1	2.24	0.74-6.78	---	---	---	---	---
Zinc salt
Acetate	5	0.96	0.89-1.04	0.83-1.11	54.3	0.0037	0.0000 - 0.0118	25.1
Gluconate	7	0.91	0.87-0.95	0.87-0.95	0.0	0.0000	0.0000 - 0.0026	---
Methionate	3	0.95	0.76-1.19	0.63-1.42	74.6	0.0267	0.0005 - 0.1466	37.8
Sulphate	18	0.84	0.85-0.93	0.60-1.18	75.2	0.0276	0.0100 - 0.0742	14.7
Not mentioned	5	0.88	0.78-1.00	0.69-1.13	60.0	0.0112	0.0000 - 0.1171	11.4
Duration of supplementation
2-10 weeks	3	0.92	0.82-1.03	0.75-1.13	70.6	0.0067	0.0049-0.0124	15.4
10-26 weeks	15	0.85	0.78-0.93	0.63-1.14	75.5	0.0190	0.0056-0.0566	11.9
27+ weeks	20	0.94	0.89-1.00	0.78-1.13	51.2	0.0072	0.0000-0.0207	23.3

N, number of study groups; SRR, summary relative risk estimate; CI, 95% confidence interval based on DerSimonian and Laird model estimates; PI, 95% prediction interval [details in supplementary note (see Additional File 3)]; τ², among-study variance; CI, confidence interval; Pr(OE), opposite effects proportion
*, For details please see text.

ISSN: 1471-2334