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Table 6 Adapted Grading31 of Recommendations Assessment, Development and Evaluation [GRADE] table for systematic reviews with meta-analysis of prognostic studies for positive outcome across a range of measures

From: Physical prognostic factors predicting outcome following lumbar discectomy surgery: systematic review and narrative synthesis

GRADE factor

 

Factors that may reduce the quality

Factors that may increase the quality

 

Prognostic factor

[pre-operative measures]

Number of participants

Number of studies

Number of cohorts

Estimated effect size [95% CI]

Phase (design)

Study limitations

Inconsistency

Indirectness

Imprecision

Publication bias

Moderate/ large effect size

Dose effect

Overall quality

Oswestry Disability Index [ODI]

399

2

2

Unclear

1

✓

x

✓

x

x

x

x

+

Very low

Duration of back pain

360

2

2

Unclear

1

x

✓

✓

x

x

✓

x

+

Very low

Duration of leg pain

713

5

5

Unclear

1

✓

x

✓

✓

✓

x

x

++

Low

Severity leg pain

488

3

3

Unclear

1

✓

x

✓

✓

✓

x

x

++

Low

Severity back pain

399

2

2

Unclear

1

✓

x

✓

x

x

✓

x

+

Very low

EuroQol-5 Dimension [EQ-5D]

140

1

1

Unclear

1

✓

x

✓

✓

x

x

x

+

Very low

Ipsilateral Straight Leg Raise [SLR]

100

1

1

Unclear

1

x

x

✓

x

x

x

x

+

Very low

Forward bend

100

1

1

Unclear

1

x

x

✓

x

X

x

x

+

Very low

  1. GRADE factors: ✓, no serious limitations; X, serious limitations [or not present for moderate/large effect size]; unclear, unable to rate item based on available information. For overall quality of evidence: +, very low; ++, low; +++, moderate; ++++, high