Scolaris Content Display Scolaris Content Display

Study flow diagram.
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Figure 1

Study flow diagram.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies. Three studies are included in this review.
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Figure 2

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies. Three studies are included in this review.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
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Figure 3

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 1 Proportion of patients who received a blood transfusion.
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Analysis 1.1

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 1 Proportion of patients who received a blood transfusion.

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 2 Haemoglobin levels pre‐treatment (g/dL).
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Analysis 1.2

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 2 Haemoglobin levels pre‐treatment (g/dL).

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 3 Haemoglobin levels at end of treatment pre‐op (g/dL).
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Analysis 1.3

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 3 Haemoglobin levels at end of treatment pre‐op (g/dL).

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 4 Haemoglobin levels after treatment post‐op (g/dL).
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Analysis 1.4

Comparison 1 Iron therapy versus placebo or no iron therapy, Outcome 4 Haemoglobin levels after treatment post‐op (g/dL).

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 1 Haemoglobin level pre‐treatment (g/dL).
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Analysis 2.1

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 1 Haemoglobin level pre‐treatment (g/dL).

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 2 Haemoglobin level post‐treatment pre‐op (g/dL).
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Analysis 2.2

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 2 Haemoglobin level post‐treatment pre‐op (g/dL).

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 3 Ferritin level pre‐treatment (ɥg/L).
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Analysis 2.3

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 3 Ferritin level pre‐treatment (ɥg/L).

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 4 Ferritin level post‐treatment (ɥg/L).
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Analysis 2.4

Comparison 2 Iron therapy: Intravenous versus oral administration, Outcome 4 Ferritin level post‐treatment (ɥg/L).

Summary of findings for the main comparison. Iron therapy versus placebo or no iron therapy for pre‐operative anaemia

Iron therapy versus placebo or no iron therapy for pre‐operative anaemia

Patient or population: Patients with pre‐operative anaemia
Settings: Major surgery
Intervention: Iron therapy versus placebo or no iron therapy

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk

Corresponding risk

Control

Iron therapy

Proportion of patients who received a blood transfusion

635 per 1000

356 per 1000
(171 to 749)

RR 0.56
(0.27 to 1.18)

38
(2 studies)

⊕⊕⊝⊝
low1

Amount of blood transfused per patient (in units)

Data from two small studies could not be combined as they were skewed and reported as medians and ranges. One RCT in 18 people reported a difference in medians of 0 (interquartile range: 1) with iron therapy. Another RCT in 20 people reported a median difference of 1 unit with iron therapy (range 0 to 2).

38
(2 studies)

⊕⊕⊝⊝
low1

It is not possible to combine the data because they are skewed. These are the raw data.

Post‐operative mortality

This outcome was not reported in either of the two studies available.

Post‐operative morbidity

This outcome was not reported in either of the two studies available.

Any validated measure of quality of life

This outcome was not reported in either of the two studies available.

Haemoglobin levels at end of treatment pre‐op (g/dL)

mean 11.9 g/dL (SD 2.6)

mean 11.2 g/d L(SD 1.95)

The mean haemoglobin levels at end of treatment pre‐op (g/dl) in the intervention groups was 0.7 g/dL lower
(2.82 lower to 1.42 higher)

18
(1 study)

⊕⊕⊝⊝
low2

Data from one study; the raw data are presented.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio; MD: mean difference; g/dL: grams per decilitre of blood.

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 Only two small randomised control trials and a subset of anaemic patients resulting in a very small number of participants.
2 Only one study with a small number of participants available.

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Summary of findings for the main comparison. Iron therapy versus placebo or no iron therapy for pre‐operative anaemia
Summary of findings 2. Iron therapy: Intravenous versus oral administration for pre‐operative anaemia

Iron therapy: Intravenous versus oral administration for pre‐operative anaemia

Patient or population: Patients with pre‐operative anaemia
Settings: Major surgery
Intervention: Iron therapy: Intravenous versus oral administration

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk

Corresponding risk

Oral iron therapy

Intravenous iron therapy

Proportion of patients who received a blood transfusion

This outcome was not reported in the one study available.

Amount of blood transfused per patient (in units)

This outcome was not reported in the one study available.

Post‐operative mortality

This outcome was not reported in the one study available.

Post‐operative morbidity

This outcome was not reported in the one study available.

Any validated measure of quality of life

This outcome was not reported in the one study available.

Haemoglobin levels at end of treatment pre‐op (g/dL)

mean 8.6 g/dL (SD 1.4)

mean 10.5 g/dL (SD 1.4)

The mean haemoglobin levels at end of treatment pre‐op (g/dl) in the intravenous group was
1.9 g/dL higher
(1.16 to 2.64 higher)

56
(1 study)

⊕⊕⊝⊝
low1,2

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
g/dL: grams per decilitre of blood.

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 Study excluded those with less than 80% compliance with therapy and compliance was lower in the oral administration group.
2 Only one study with a small number of participants.

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Summary of findings 2. Iron therapy: Intravenous versus oral administration for pre‐operative anaemia
Comparison 1. Iron therapy versus placebo or no iron therapy

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Proportion of patients who received a blood transfusion Show forest plot

2

38

Risk Ratio (M‐H, Fixed, 95% CI)

0.56 [0.27, 1.18]

2 Haemoglobin levels pre‐treatment (g/dL) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

3 Haemoglobin levels at end of treatment pre‐op (g/dL) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

4 Haemoglobin levels after treatment post‐op (g/dL) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 1. Iron therapy versus placebo or no iron therapy
Comparison 2. Iron therapy: Intravenous versus oral administration

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Haemoglobin level pre‐treatment (g/dL) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Subtotals only

2 Haemoglobin level post‐treatment pre‐op (g/dL) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Subtotals only

3 Ferritin level pre‐treatment (ɥg/L) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Subtotals only

4 Ferritin level post‐treatment (ɥg/L) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Subtotals only

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Comparison 2. Iron therapy: Intravenous versus oral administration