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Table 1 Quality assessment of overall evidence for effect of zinc supplementation (alone) in reducing morbidity and mortality in children > 5 years of age in developing countries

From: Preventive zinc supplementation in developing countries: impact on mortality and morbidity due to diarrhea, pneumonia and malaria

No of studies (ref)

Study Design

Limitations

Consistency

Generalizability to Population of Interest

Generalizability to intervention of interest

Relative Risk (95% CI)

Outcome: All-cause mortality: Quality of evidence: Low

7

RCTs

Sequence generation and allocation concealment was unclear in few of the included studies

I2= 50%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.91 (0.82-1.01)

Outcome: Diarrhea specific mortality: Quality of evidence: Low

4

RCTs

Allocation concealment was unclear in two of the included studies

I2=0%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.82 (0.64-1.05)

Outcome: Diarrhea specific morbidity: Quality of evidence: Moderate

14

RCTs

Sequence generation and allocation concealment was unclear in few of the included studies

I2=79%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.87 (0.81-0.94)

Outcome: Pneumonia specific mortality: Quality of evidence: Low

4

RCTs

Allocation concealment was unclear in two of the included studies

I2= 39%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.85 (0.65-1.11)

Outcome: Pneumonia specific morbidity: Quality of evidence: Moderate

6

RCTs

Sequence generation and allocation concealment was unclear in few of the included studies

I2=0%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.81 (0.73-0.90)

Outcome: Malaria specific mortality: Quality of evidence: Low

1

RCT

None

NA

Study conducted in Zanzibar

Dose of supplementation was 10 mg/dl for children > 1 year and 5mg/day for children < 1 years.

0.90 (0.77-1.06)

Outcome: Malaria specific morbidity: Quality of evidence: Low

4

RCTs

Allocation concealment was unclear in two of the included studies

I2=0%

Yes (all studies were conducted in developing countries)

The median dose of supplementation was 10 mg/day and median duration of supplementation was for 6 months.

0.92 (0.82-1.04)